AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JUNE 6, 2003
                                                     REGISTRATION NO. 333-103721
================================================================================


                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                 ---------------


                                 AMENDMENT NO. 1
                                       TO
                                    FORM S-3


                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                 ---------------

                         California Water Service Group
             (Exact name of registrant as specified in its charter)

                                    Delaware
         (State or other jurisdiction of incorporation or organization)

                                   77-0448994
                     (I.R.S. Employer Identification Number)

                             1720 North First Street
                               San Jose, CA 95112
                                  408-367-8200
    (Address, including zip code, and telephone number, including area code,
                  of registrant's principal executive offices)

                                 Richard D. Nye
              Vice President, Chief Financial Officer and Treasurer
                         California Water Service Group
                             1720 North First Street
                               San Jose, CA 95112
                                 (408) 367-8200
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                 with copies to:
       Thomas G. Reddy, Esq.                        Jonathan A. Koff, Esq.
      Venrice R. Palmer, Esq.                         Chapman and Cutler
       Bingham McCutchen LLP                        111 West Monroe Street
Three Embarcadero Center, 18th Floor             Chicago, Illinois 60603-4080
  San Francisco, California 94111                       (312) 845-3000
           (415) 393-2000                             Fax (312) 701-2361
         Fax (415) 393-2286

                                 ---------------

    Approximate  date of commencement of proposed sale to the public:  From time
to time after the effective date of this registration statement.

                                 ---------------

    If the only  securities  being  registered  on this form are  being  offered
pursuant to dividend or interest  reinvestment plans, please check the following
box. [ ]


    If any of the securities  being registered on this form are to be offered on
a delayed or continuous  basis  pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. [X]

    If this form is filed to  register  additional  securities  for an  offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration  statement  number  of the  earlier
effective registration statement for the same offering. [ ]

    If this form is a  post-effective  amendment  filed  pursuant to Rule 462(c)
under the  Securities  Act,  check the following box and list the Securities Act
registration  statement number of the earlier effective  registration  statement
for the same offering. [ ]

    If delivery of the  prospectus  is expected to be made pursuant to Rule 434,
please check the following box. [X]



THE REGISTRANT HEREBY AMENDS THIS  REGISTRATION  STATEMENT ON SUCH DATE OR DATES
AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT  SHALL FILE
A FURTHER AMENDMENT WHICH SPECIFICALLY  STATES THAT THIS REGISTRATION  STATEMENT
SHALL  THEREAFTER  BECOME  EFFECTIVE  IN  ACCORDANCE  WITH  SECTION  8(a) OF THE
SECURITIES  ACT OF  1933  OR  UNTIL  THE  REGISTRATION  STATEMENT  SHALL  BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION,  ACTING PURSUANT TO SAID SECTION 8(a),
MAY DETERMINE.




The  information in this  prospectus is not complete and may be changed.  We may
not sell  these  securities  until the  registration  statement  filed  with the
Securities and Exchange Commission is effective. This prospectus is not an offer
to  sell  these  securities  and it is not  soliciting  an  offer  to buy  these
securities in any state where the offer or sale is not permitted.

                SUBJECT TO COMPLETION, DATED _____________, 2003

                         CALIFORNIA WATER SERVICE GROUP
                             1720 North First Street
                               San Jose, CA 95112
                                  408-367-8200

                                 ---------------


                                  $120,000,000
                DEBT SECURITIES, PREFERRED STOCK AND COMMON STOCK

                                 ---------------


    California  Water  Service  Group  plans to offer to the public from time to
time:

    o    ourunsecured debt securities  consisting of debentures,  notes or other
         evidences of indebtedness;

    o    our preferred stock; and

    o    our common stock.

    Our  common  stock  trades on the New York Stock  Exchange  under the symbol
"CWT."

    This prospectus provides you with a general description of the securities we
may offer. We may offer the securities as separate  series,  in amounts,  prices
and on terms  determined at the time of the sale. When we offer  securities,  we
will provide a prospectus supplement or a term sheet describing the terms of the
specific securities offered,  including the offering price. You should read both
this prospectus and any prospectus  supplement or term sheet,  together with the
additional  information  described  under the  heading  "Where You Can Find More
Information"  beginning  on page 21 of this  prospectus,  before  you make  your
investment decision.

    We will sell the securities to underwriters or dealers,  through agents,  or
directly to investors.

                                ---------------

    Neither  the  SEC  nor any  state  securities  commission  has  approved  or
disapproved of these  securities or determined if this prospectus is truthful or
complete. Any representation to the contrary is a criminal offense.

    This prospectus may not be used to sell securities  unless  accompanied by a
prospectus supplement or term sheet.

                                 ---------------

                   The date of this prospectus is ______, 2003




                                TABLE OF CONTENTS



About This Prospectus                                                         3
Ratios of Earnings To Fixed Charges and Preferred Stock Dividends             3
Forward-Looking Statements                                                    3
Risk Factors                                                                  4
California Water Service Group                                                8
California Water Service Group--Service Area                                  9
Use of Proceeds                                                              10
Description of Debt Securities                                               10
Description of Preferred Stock                                               16
Description of Common Stock                                                  19
Rights Agreement                                                             20
Anti-Takeover Effects of Our Certificate of Incorporation
  and Bylaws and Delaware Law                                                22
Plan of Distribution                                                         22
Legal Matters                                                                24
Experts                                                                      24
Where You Can Find More Information                                          24



                                       2




                              ABOUT THIS PROSPECTUS

    This  prospectus is part of a registration  statement that we filed with the
SEC using a "shelf" registration process.  Under the shelf process, we may, from
time to time,  issue and sell to the public any  combination  of the  securities
described in the  registration  statement,  and in any prospectus  supplement or
term  sheet,  in  one  or  more  offerings  up  to  a  total  dollar  amount  of
$120,000,000.




        RATIOS OF EARNINGS TO FIXED CHARGES AND PREFERRED STOCK DIVIDENDS

    The following table sets forth our consolidated  ratios of earnings to fixed
charges and earnings to fixed  charges and  preferred  stock  dividends  for the
periods shown. For the purposes of calculating these ratios, earnings consist of
income from continuing  operations before income taxes and fixed charges.  Fixed
charges consist of interest on indebtedness,  amortization of debt premium,  the
interest  component  of rentals  and,  with  respect to the ratio of earnings to
fixed  charges  and  preferred   stock   dividends,   preferred  stock  dividend
requirements.





                                              Twelve Months
                                                  ended               Year Ended December 31,
                                            March 31, 2003 (1)    2002   2001   2000   1999   1998
                                            ------------------   -----  -----  -----  -----  -----
                                                                            
Ratio of Earnings to Fixed Charges                 2.36           2.64   2.41   3.00   3.42   3.24
Ratio of Earnings to Fixed Charges and
Preferred Stock Dividends                          2.33           2.60   2.37   2.95   3.36   3.19

(1) The business is seasonal,  therefore  information for the three-month period
ended March 31, 2003 would not be indicative of the results of the entire year.


                           FORWARD-LOOKING STATEMENTS


    This prospectus,  any prospectus supplement or term sheet, and the documents
we have incorporated by reference may contain  forward-looking  statements.  The
forward-looking  statements  are  intended  to  qualify  for the  "safe  harbor"
treatment  established  by the Securities Act of 1933, as amended by the Private
Securities Litigation Reform Act of 1995.  Forward-looking  statements are based
on currently available  information,  expectations,  estimates,  assumptions and
projections,  and  management's  judgment  about the company,  the water utility
industry  and general  economic  conditions.  Words like  "expects,"  "intends,"
"plans,"  "believes,"   "estimates,"   "assumes,"   "anticipates,"   "projects,"
"predicts,"  "forecasts" or variations of these words or similar expressions are
intended to identify forward-looking  statements. The forward-looking statements
are not guarantees of future performance. They are based on numerous assumptions
that  we  believe  are  reasonable,  but  they  are  open  to a  wide  range  of
uncertainties  and  business  risks.  Consequently,   actual  results  may  vary
materially from what is contained in a forward-looking statement.  Factors which
may cause actual results to be different than expected or anticipated include:


     o   governmental and regulatory commissions' decisions;

     o   changes in regulatory commissions' policies or procedures;

     o   the  timeliness  of regulatory  commissions'  actions  concerning  rate
         relief;

     o   new legislation;

     o   electric power interruptions;

     o   increases  in  suppliers'  prices  and  the  availability  of  supplies
         including water and power;

                                       3


     o   fluctuations in interest rates;

     o   changes in environmental compliance and water quality requirements;

     o   acquisitions  and  our  ability  to  successfully   integrate  acquired
         companies;

     o   the ability to successfully implement business plans;

     o   changes in customer water use patterns;

     o   the impact of weather on water sales and operating results;

     o   access to sufficient capital on satisfactory terms;

     o   civil  disturbances or terrorist threats or acts, or apprehension about
         the possible future occurrences of acts of this type;

     o   restrictive  covenants  in or  changes  to the  credit  ratings  on our
         current  or future  debt that could  increase  our  financing  costs or
         affect our ability to borrow,  make payments on debt or pay  dividends;
         and

     o   other risks and unforeseen events.

    When  considering  forward-looking  statements,  you should keep in mind the
cautionary  statements in this  prospectus,  any  prospectus  supplement or term
sheet and the documents  incorporated  by reference.  We assume no obligation to
provide public updates of forward-looking statements.



                                  RISK FACTORS

Our business is heavily  regulated and decisions by regulatory  commissions  and
changes in laws and regulations can significantly affect our business.

    California  Water  Service  Company,   New  Mexico  Water  Service  Company,
Washington  Water  Service  Company and Hawaii Water Service  Company,  Inc. are
regulated  public  utilities  which provide water service to our customers.  The
rates  that the  companies  charge  their  water  customers  are  subject to the
jurisdiction  of the  regulatory  commission  in the states in which we operate.
These  commissions  set water rates for each  operating  district  independently
because the systems are not  interconnected.  The  commissions  authorize  us to
charge  rates  which  they  consider  to be  sufficient  to  recover  our normal
operating  expenses,  to  provide  funds  for  adding  new  or  replacing  water
infrastructure,  and to allow us to earn what the  commissions  consider to be a
fair and reasonable return on our invested capital.

    Our ability to meet our  financial  objectives  is dependent  upon the rates
authorized by the commissions.  We periodically file rate increase  applications
with the  commissions.  The ensuing  administrative  and hearing  process may be
lengthy and costly. We can provide no assurances that our rate increase requests
will be granted by the commissions. Even if approved, there is no guarantee that
approval will be given in a timely manner or at a sufficient  level to cover our
expenses and provide a reasonable  return on our  investment.  If the authorized
rates are  insufficient  to cover  operating  expenses  and capital  expenditure
requirements,  and allow a reasonable  return on invested  capital,  or the rate
increase decisions are delayed, our earnings may be adversely affected.


Our  liquidity  and  earnings  could  be  adversely  affected  by  increases  in
electricity prices.

    Purchased  power  expense  represents  electricity  purchased to operate the
wells and pumps  which are needed to supply  water to our  customers.  Purchased
power is a significant operating expense.  During 2002 and 2001, purchased power
expense  represented  10% of our total operating  costs.  These costs can and do
increase  unexpectedly  and in  substantial  amounts,  as occurred in California
during 2001 when rates we paid for electricity  increased 48%. The


                                       4



increases are beyond our control.  California  regulation  regarding recovery of
increases in electric  rates  changed in 2001.  For over 20 years prior to 2001,
the California  Public  Utilities  Commission  allowed recovery of electric rate
increases under its operating rules.  However,  in 2001, the commission  revised
its rules and  deferred  our  recovery  of the higher  electric  costs until the
filing  of a  general  rate  case.  In 2003,  the  California  Public  Utilities
Commission  granted  recovery of a majority of these higher costs incurred up to
November,  2001. The remainder of these costs will be incorporated  into general
rate case filings.

    We cannot provide  assurance that we will be allowed to recover the electric
rate increases paid since  November 2001 or future  increases.  The inability to
recover  the higher  costs  affects  our cash  flows and can affect our  capital
resources and liquidity.  Also, it may adversely  affect profit margins,  unless
the regulatory  commission  authorizes us to seek  reimbursement  of those costs
from our customers.


Changes in water supply costs directly affect our earnings.

    The cost to obtain water for delivery to our customers  varies  depending on
the sources of supply,  wholesale  suppliers'  prices and the  quantity of water
produced  to supply  customer  water  usage.  Our  source  of  supply  varies by
operating  district.  Certain  districts  obtain all of their supply from wells,
some  districts  purchase all of the supply from  wholesale  suppliers and other
districts obtain the supply from a combination of well and purchased  sources. A
small  portion of the  supply is from  surface  sources  and  processed  through
company-owned water treatment plants. On average, slightly more than half of the
water  delivered to  customers  is pumped from wells or received  from a surface
supply with the remainder  purchased from wholesale  suppliers.  During 2002 and
2001, the cost of purchased  water for delivery to customers  represented 33% of
our total operating costs.

    Wholesaler  water suppliers may increase their prices for water delivered to
us based on factors that affect their  operating  costs. As with electric rates,
purchased  water rate  increases  are beyond our  control.  In  California,  our
ability  to  recover  increases  in the cost of  purchased  water is  subject to
decisions  by  the  regulatory  commission.  The  same  process  for  recovering
purchased power rate increases applies to our ability to recover purchased water
cost increases.  The changes in the  commission's  rules  regarding  recovery of
electricity  rate  increases  apply to our  recovery of higher  purchased  water
costs. If we are not allowed to recover the higher costs, our cash flows and our
capital  resources and liquidity can be negatively  impacted.  Also,  our profit
margins  may be  adversely  affected,  unless the  commissions  allow us to seek
reimbursement of those costs from our customers.


Environmental regulation has increased, and is expected to continue to increase,
our operating costs.

    Our water and wastewater  services are governed by various federal and state
environmental  protection  and  health and safety  laws and  regulations.  These
provisions  establish  criteria for drinking  water and for discharges of water,
wastewater and airborne substances.  If we violate these provisions, we could be
subject to substantial fines or otherwise sanctioned.

    Environmental  laws are complex and change  frequently.  They have tended to
become more  stringent over time. As new or stricter  standards are  introduced,
they  could  raise  our  operating  costs.  There can be no  assurance  that the
commissions  would  approve  rate  increases  to  enable  us  to  recover  these
additional compliance costs.

    We are  required  to test  our  water  quality  for  certain  chemicals  and
potential  contaminants on a regular basis. If the test results indicate that we
exceed  allowable  limits,  we may be required  either to commence  treatment to
remove the contaminant or to develop an alternate water source.  Either of these
results may be costly,  and there can be no assurance that the commissions would
approve rate increases to enable us to recover these additional compliance costs

    All of the above factors may have a material adverse effect on our business,
financial position and results of operations.


The adequacy of our water supplies  depends upon a variety of factors beyond our
control. Interruption in the water supply may adversely affect our earnings.


                                       5


    We depend on an adequate  water  supply to meet the present and future needs
of our  customers.  Whether we have an adequate  supply varies  depending upon a
variety of factors, including:

         o        rainfall;

         o        the amount of water stored in reservoirs;

         o        underground water supply from which well water is pumped;

         o        changes in the amount of water used by our customers;

         o        water quality;

         o        legal limitations on water use, such as rationing restrictions
                  during a drought; and

         o        population growth.


    Also,  the water  business is seasonal.  The normal water use pattern within
our service  territories  sees the highest  customer  usage and highest  revenue
during the warmer  summer  months due  primarily to  increased  summer usage for
watering  outside  landscape,  cooling and swimming  pools.  Customer  usage and
revenue are lower during the cool, rainy winter months.  Demand also varies with
rainfall  levels.  If summer  temperatures  are cooler  than normal or the rainy
season extends into the summer months or begins early in the fall months, any of
these factors can cause a decline in customer usage and result in lower revenue.

    Drought  conditions  may affect our  ability to serve our current and future
customers,  and may affect our customers' use of water.  Restrictions imposed on
the amount of water  customers are allowed to use during a drought may result in
decreased customer  billings.  Customers may use less water even after a drought
has passed  because of  conservation  patterns  developed  during the drought or
lower use for any reason could lead to continued lower revenue.

    Since the September 11, 2001 terrorist attacks,  we have heightened security
at our  facilities and taken added  precautions  for the safety of our employees
and water we deliver to our customers.  We have also assigned a high priority to
completing  work necessary to comply with new  Environmental  Protection  Agency
requirements  concerning  security  of  water  facilities.  These  actions  have
increased our costs.

All of these factors may adversely affect our earnings and financial condition.


Our business requires significant capital expenditures and may suffer if we fail
to secure appropriate funding.

    The water utility business is capital-intensive.  We invest significant sums
to add or replace  property,  plant and  equipment.  We fund these projects from
cash received from operations and funds received from developers. We also borrow
funds from banks under short-term bank lending arrangements. We may seek to meet
our long-term  capital needs by raising equity through common or preferred stock
issues or issuing debt obligations.

    Water  shortages  may  adversely  affect  us by  causing  us to rely on more
purchased water.  This could cause increases in capital  expenditures  needed to
build pipelines to secure alternative water sources.

    Our rate increase  applications  are designed to recover our  investments in
utility plant. We cannot assure you that the rates the commissions will allow us
to charge will be sufficient for this purpose.

    Moody's  Investor  Services  Inc.  and  Standard  & Poors  issue  ratings on
California Water Service Company's ability to repay debt obligations. The credit
rating  agencies  could  downgrade  our  credit  rating  based on reviews of our
financial  performance  and  projections  or upon the occurrence of other events
that could impact our business outlook.  In 2002, Moody's Investor Services Inc.
and Standard & Poors did lower the ratings on California Water Service Company's
first mortgage bonds. The rating actions were attributed to delays in receipt of
decisions  by the  California  Public  Utilities  Commission  for rate  increase
applications and ongoing capital  expenditures to maintain water  infrastructure
and meet environmental compliance  requirements.  A downgrade could increase our
cost of capital by causing  potential


                                       6


investors to require an higher  interest  rate due to a perceived  risk increase
related to our ability to repay outstanding debt  obligations.  Lower ratings by
the agencies  could also restrict our ability to access equity and debt capital.
We cannot assure you that the rating agencies will maintain  ratings which allow
us to borrow under advantageous conditions and at reasonable interest rates.

    We cannot assure you that our existing  funding  sources will continue to be
adequate or that the cost of funds will remain at levels permitting us to remain
profitable.

    Any of  these  factors  may  have an  adverse  effect  on our  earnings  and
financial condition.


Risks  associated with potential  acquisitions or divestitures or  restructuring
may adversely affect us.

    We may seek to acquire or invest in other companies, technologies,  services
or products  that  complement  our  business.  We cannot assure you that we will
succeed in finding  attractive  acquisition  candidates  or  investments.  These
transactions  may  result in the  issuance  of equity  securities  that could be
dilutive  if the  acquisition  or  business  opportunity  does  not  develop  in
accordance  with  our  business  plan.  They  may  also  result  in  significant
write-offs  and an increase in our debt.  The  occurrence of any of these events
could have a material  adverse effect on our business,  financial  condition and
results of operations.

    Any of these  transactions  could involve  numerous  additional  risks.  For
example, we may experience  difficulty in getting required regulatory approvals.
We may also have  difficulty  assimilating  a new  business  or  separating  old
businesses.  Transactions such as these may also divert  management's  attention
from other business concerns and otherwise disrupt our business.  We might see a
loss  of  key  employees  from  our  acquisition  targets  and as a  result  the
integration of the new business  opportunity into our existing business might be
more difficult.

    All of these  events may have a  material  adverse  effect on our  business.
There can be no assurance that we will be successful in overcoming  these or any
other significant risks encountered.


                                       7


                         CALIFORNIA WATER SERVICE GROUP


    The company is a holding  company  whose  business is carried on through its
five wholly-owned operating subsidiaries:  California Water Service Company, CWS
Utility  Services,  Washington Water Service  Company,  New Mexico Water Service
Company and Hawaii Water  Service  Company,  Inc. We were formed on December 31,
1997.

    California  Water Service Company,  Washington  Water Service  Company,  New
Mexico  Water  Service  Company  and Hawaii  Water  Service  Company,  Inc.  are
regulated  public  utilities.  Their  assets and  operating  revenues  currently
comprise substantially all of our assets and all of our utility revenues.  Their
primary   business  is  the   production,   purchase,   storage,   purification,
distribution and sale of water for domestic,  industrial,  public and irrigation
uses, and for fire protection.  Their assets consist of land, buildings,  wells,
tanks, pipes and equipment necessary for water operations.

    We also provide non-regulated  water-related  services under agreements with
municipalities and other private companies.  The non-regulated  services include
full water  system  operations,  and billing and  meter-reading  services.  Many
non-regulated  operations are conducted by CWS Utility  Services under contracts
with other private companies and  municipalities.  CWS Utility Services operates
water  systems,  leases  communication  antenna sites,  operates  recycled water
systems,  provides meter reading and customer services, and conducts real estate
sales  of  surplus  properties.  The  regulated  companies  also  carry  on some
non-regulated operations.  Income and expenses from non-regulated operations are
reported under "Other income and expenses, net" on our income statement.


    California Water Service Company is the largest of the operating  companies,
representing 96% of our regulated customers and 98% of our operating revenue. It
began  operations in 1926 and supplies water service to 440,500  customers in 75
California   communities   through  25  separate  water  systems  or  districts.
California Water Service  Company's 24 regulated  systems,  which are subject to
regulation  by  the  California  Public  Utilities  Commission,   serve  434,400
customers.  An additional  6,100  customers  receive service through a long-term
lease  of the  City  of  Hawthorne's  water  system,  which  is not  subject  to
regulation by the Utilities  Commission.  The Utilities Commission requires that
water rates for each regulated district be independently  determined.  Rates for
the City of Hawthorne  system are  established  in accordance  with an operating
agreement and are subject to ratification by the City of Hawthorne City Council.
Fees for other operating  agreements are based on contracts negotiated among the
parties.

    Washington  Water Service  Company was formed in 1999.  Its regulated  water
utility  operations are subject to the jurisdiction of the Washington  Utilities
and Transportation Commission.  Washington Water provides domestic water service
to 14,400  customers  in the Tacoma  and  Olympia  areas.  An  additional  3,900
customers are served under operating agreements with private owners.  Operations
under these agreements are not subject to regulation by the Washington Utilities
and Transportation Commission.

    New Mexico Water Service  Company was formed in 2000. It acquired the assets
of Rio Grande  Utilities  Corporation  in July 2002.  New Mexico Water  provides
service to 2,400 water and 1,700 wastewater  customers south of Albuquerque.  It
also provides non-regulated meter reading services under contract to a county in
New Mexico.


    On April 30,  2003,  we acquired  the  Kaanapali  Water  Corporation  for an
initial payment of $7.5 million in cash. After  completing the acquisition,  the
entity's name was changed to Hawaii Water  Service  Company,  Inc.  Hawaii Water
Service Company,  Inc. provides water utility services to 500 customers in Maui,
Hawaii.  It had 2002  revenues  of $3.0  million,  and has net  plant  excluding
contributions in aid of construction of  approximately  $7.2 million and current
assets of $0.2  million.  The  acquisition  was  approved  by the Hawaii  Public
Utilities  Commission in March 2003. The final purchase price will be determined
after certain events have occurred,  principally the  determination of rate base
after  filing  for  a  general  rate  case  with  the  Hawaii  Public  Utilities
Commission. At that time, the purchase price could be increased or decreased.



                                       8



                                    [GRAPHIC]


Map showing:

State of Washington Added in 1999, with map points for Olympia, Harbor and South
Sound

State of California,  with map points for Chico, Willows, Oroville,  Marysville,
Redwood Valley, (Sacramento),  Dixon, Stockton, (San Francisco),  Bayshore, Bear
Gulch, Los Altos, Salinas, King City, Livermore, General Office (San Jose), Kern
River Valley, Selma, Visalia,  Westlake,  Rancho Dominguez,  (Los Angeles), East
Los Angeles, Antelope Valley, Bakersfield

State of New Mexico  Added in 2002,  with map points for Los  Alamos,  Santa Fe,
Belen, Alberqueque


State of Hawaii: Added in April 2003, with map points for (Honolulu), Kaanapali


     o   California Water Service Company

     o   Washington Water Service Company

     o   New Mexico Water Service Company

     o   Hawaii Water Service Company, Inc.




                                [GRAPHIC OMITTED]




                                       9


                                 USE OF PROCEEDS

    We intend to add the net  proceeds  from the sale of the  securities  to our
general  funds to be used for  general  corporate  purposes,  which may  include
investment in subsidiaries, working capital, capital expenditures,  repayment of
short-term borrowings,  refinancing of existing long-term debt, acquisitions and
other business opportunities.

                         DESCRIPTION OF DEBT SECURITIES

    The debt  securities  will be unsecured and will rank on parity with all our
other unsecured and unsubordinated indebtedness. We may issue debt securities in
one or more  series  under  an  indenture  between  us and  U.S.  Bank  National
Association,  as trustee.  The form of indenture has been filed as an exhibit to
the  registration  statement of which this  prospectus is a part.  The following
description  summarizes the material  terms of the debt  securities and we refer
you to the indenture for the full text,  which we incorporate by reference.  The
indenture  will be subject to and governed by the Trust  Indenture  Act of 1939.
The indenture and the debt  securities will also be governed by and construed in
accordance with the laws of the State of California.

The Debt Securities

    The  indenture  does not limit the  aggregate  principal  amount of the debt
securities  or of any  particular  series of debt  securities  that we may issue
under it. We are not required to issue debt securities of any series at the same
time nor must the debt  securities  within any series bear  interest at the same
rate or mature on the same date.


    The debt securities are obligations  exclusively of California Water Service
Group. As a holding company, we have no material assets other than our ownership
of the common stock of our subsidiaries. Unless we say otherwise in a prospectus
supplement or term sheet,  we will rely entirely  upon  distributions  and other
amounts received from our subsidiaries to meet the payment obligations under the
debt securities.

    Our  subsidiaries  are  separate  and  distinct  legal  entities and have no
obligation,  contingent  or  otherwise,  to  pay  amounts  due  under  the  debt
securities  or  otherwise to make any funds  available to us. This  includes the
payment  of  dividends  or  other  distributions  or the  extension  of loans or
advances,  unless we say  otherwise  in a prospectus  supplement  or term sheet.
Public  utility   commissions   that  regulate  most  of  our  subsidiaries  may
effectively restrict the payment of dividends to us by our subsidiaries.

    Furthermore,  the  ability of our  subsidiaries  to make any  payments to us
would be dependent upon the terms of any credit  facilities of the  subsidiaries
and upon the  subsidiaries'  earnings,  which are  subject to  various  business
risks. In a bankruptcy or insolvency  proceeding,  claims of holders of the debt
securities   would  be  satisfied  solely  from  our  equity  interests  in  our
subsidiaries  remaining  after the  satisfaction  of claims of  creditors of the
subsidiaries.  Accordingly,  the debt securities are effectively subordinated to
existing  and  future  liabilities  of  our  subsidiaries  to  their  respective
creditors.


    We will issue debt securities only in fully registered form, without coupons
and, generally,  in denominations of $1,000 or multiples of $1,000.  Payments on
debt  securities  will be payable at the  corporate  trust  office of U.S.  Bank
National Association in San Francisco, California.

    Each  time  we  issue  a new  series  of  debt  securities,  the  prospectus
supplement  or term sheet  relating to that new series will describe the amount,
price and other terms of those debt securities. Terms may include:

     o   the title of the debt securities;

     o   any limit on the total principal amount of the debt securities;


     o   the person to whom interest on a security is payable, if other than the
         person in whose name the security is registered;

     o   the date or dates on which  principal of a series of the  securities is
         payable;


                                       10



     o   the rate or rates at which the debt securities  will bear interest,  if
         any, or the method by which the rate or rates will be determined;

     o   the record dates and payment  dates or the method by which record dates
         and payment dates will be determined;


     o   the place or places  where  the  principal  of,  premium,  if any,  and
         interest on the debt securities will be payable;

     o   the terms and conditions,  if any, on which we may choose to redeem the
         debt securities, including the amount of any premium we must pay;


     o   any  obligation  we may have to redeem or purchase the debt  securities
         pursuant to any sinking fund, purchase fund or similar provision, or at
         the option of the  holder,  and the terms and  conditions  on which the
         debt   securities  may  be  redeemed  or  purchased   because  of  that
         obligation;


     o   the  denominations in which we may issue the securities,  if other than
         $1,000 and integral multiples of $1,000;

     o   the portion of the principal amount of the debt securities that will be
         payable if the  maturity  date is  accelerated  (if the amount  will be
         different from the principal amount);


     o   the  currency,  currencies  or currency  units in which we will pay the
         principal  of and any premium and interest on the debt  securities,  if
         other than U.S.  dollars,  and the manner of determining the equivalent
         in U.S. dollars;


     o   if either  the  company  or a holder  may elect to have  payment on the
         securities  made in a currency  other than that in which the securities
         are  stated  to be  payable,  the time  within  which and the terms and
         conditions on which the company or holder may make the election;

     o   any index or formula  used to  determine  the amount of principal of or
         any  premium  or  interest  on the debt  securities  and the  manner of
         determining any of these amounts;

     o   the manner,  if any, in which we may  discharge  our  obligation on the
         securities by  establishing  a trust fund to be used for payment of the
         securities in full;


     o   whether  we will issue any debt  securities  in whole or in part in the
         form of one or more global securities;


     o   if we issue global  securities,  the identity of the depositary for the
         global securities and any provisions  regarding the transfer,  exchange
         or legending of any global  security (if they are different  from those
         described below); and


     o   other material terms of the debt securities.



    We may offer and sell debt securities at a substantial  discount below their
principal amount. If so, we will describe any applicable  special federal income
tax and other  considerations,  if any, in the relevant prospectus supplement or
term sheet.  We may also describe  certain  special  federal income tax or other
considerations,  if any,  applicable to any debt securities that are denominated
in a  currency  or  currency  unit  other  than  U.S.  dollars  in the  relevant
prospectus supplement or term sheet. We will also describe the amount payable on
these  securities if our obligation to repay the  securities is accelerated  for
any reason.




    If we  decide to issue  debt  securities  in the form of one or more  global
securities,  then we will  register  the  global  securities  in the name of the
depositary for the global  securities or the nominee of the depositary,  and the
trustee will deliver the global  securities to the  depositary for credit to the
accounts of the holders of  beneficial  interests  in the debt  securities.  The
prospectus  supplement  or term sheet will  describe the  specific  terms of the
depositary arrangement for debt securities of a series that are issued in global
form.  Neither the company,  nor the trustee,  any payment agent or the security
registrar  will  have any  responsibility  or  liability  for any  aspect of the
records  relating  to or  payments  made  on  account  of  beneficial  ownership
interests  in a global  debt  security.  They will also not be  responsible  for
maintaining,  supervising or reviewing any records  relating to these beneficial
ownership interests.





                                       11



    We will pay any  interest  due on any debt  security  to the person in whose
name the debt  security  is  registered  at the close of business on the regular
record date for interest. If we fail to pay interest on the relevant due date we
will make  payment to anyone who holds the debt  security at a future date which
the trustee  will  choose.  The  trustee  will send notice of the payment to all
those who hold the debt  security  on a date which the trustee  will  determine.
That date will be at least 10 days before the payment date.

Registration

    The trustee will  maintain a register of holders of debt  securities  and of
transfers of debt  securities.  You may  exchange  debt  securities  or register
transfers  of debt  securities  at the  trustee's  office.  We will not charge a
service fee for the registration,  transfer or exchange of debt securities,  but
we may  require a  payment  sufficient  to cover  any tax or other  governmental
charge payable in connection with registration, transfer or exchange.

Satisfaction and Discharge of the Indenture

   We will have  satisfied and  discharged the indenture and it will cease to be
in effect (except as to our  obligations to compensate,  reimburse and indemnify
the  trustee  pursuant  to the  indenture  and some other  obligations)  when we
deposit  or  cause to be  deposited  with  the  trustee,  in  trust,  an  amount
sufficient to pay and discharge the entire  indebtedness  on the debt securities
not previously delivered to the trustee for cancellation, for the principal (and
premium,  if any) and  interest  to the date of the  deposit  (or to the  stated
maturity  date or earlier  redemption  date for debt  securities  that have been
called for redemption).

Remedies


    An event of default with  respect to debt  securities  of any series  issued
under the indenture is any one of the following  events (unless  inapplicable to
the particular series, specifically modified or deleted as a term of that series
or otherwise modified or deleted in a supplemental indenture):

    o    we fail to pay any  interest  on any debt  security of that series when
         due, and the failure has continued for 30 days;

    o    we fail to pay principal of or premium, if any, on any debt security of
         that series when due;

    o    we fail to perform any other  covenant in the  indenture  (other than a
         covenant  included in the indenture  solely for the benefit of a series
         of debt  securities  other  than  that  series),  and the  failure  has
         continued  for 60 days after we receive  written  notice as provided in
         the indenture;

    o    events of bankruptcy, insolvency or reorganization; and

    o    any other  event  defined as an event of default  with  respect to debt
         securities of a particular series.

    If an event of default with respect to any series of debt securities  occurs
and is continuing,  the trustee or the holders of not less than 25% in principal
amount of the  outstanding  debt  securities  of that  series  may  declare  the
principal  amount (or, if any debt securities of that series are discounted debt
securities,  a portion of the principal  amount that the terms of the series may
specify)  of all  debt  securities  of that  series  to be  immediately  due and
payable. Under some circumstances, the holders of a majority in principal amount
of the  outstanding  debt  securities  of that series may rescind and annul that
declaration  and its  consequences.  The  prospectus  supplement  or term  sheet
relating to any series of debt  securities  which are discounted debt securities
will specify the particular  provisions relating to acceleration of a portion of
the principal amount of the discounted debt securities upon the occurrence of an
event of default and the continuation of the event of default.

    Subject to the  provisions  of the  indenture  relating to the duties of the
trustee in case an event of default occurs and is continuing, the trustee is not
obligated  to exercise  any of its rights or powers  under the  indenture at the
request or  direction  of any of the holders  unless the holders have offered to
the trustee  reasonable  security or indemnity.  Subject to any  provisions  for
security and indemnification of the trustee and other rights of the trustee, the
holders of a majority

                                       12


in principal  amount of the  outstanding  debt securities of any series have the
right to direct the time, method and place of conducting any proceedings for any
remedy  available to the trustee or exercising  any trust or power  conferred on
the trustee with respect to the debt securities of that series.

    The holder of any debt  security  will have an  absolute  and  unconditional
right to receive  payment of the  principal of and any premium  and,  subject to
limitations  specified  in the  indenture,  interest  on a debt  security on its
stated maturity date (or, in the case of redemption, on the redemption date) and
to sue to enforce any of these payments.

   We must  furnish to the trustee an annual  statement  that to the best of our
knowledge we are not in default in the  performance and observance of any terms,
provisions  or  conditions  of the  indenture  or, if there has been a  default,
specifying each default and its status.


The Trustee

    The company has appointed U.S. Bank National Association, a national banking
association,  to serve as  trustee.  We or a majority of the holders of the debt
securities  may  replace  the  trustee  for  certain  reasons  provided  in  the
indenture.  The trustee is to carry out those duties  assignable to it under the
indenture.  The trustee  assumes no  responsibility  for the  nature,  contents,
accuracy or  completeness of the information set forth in this prospectus or any
relevant prospectus supplement or for the recitals contained in the indenture or
the  debt  securities   issued  under  the  indenture,   or  for  the  validity,
sufficiency, or legal effect of any of these documents.

    Furthermore,  the  trustee  has  no  oversight  responsibility  and  is  not
accountable for our use or application of any of the debt securities the trustee
authenticates or delivers,  or for our use or application of the proceeds of the
debt securities. The trustee has not evaluated the risks, benefits, or propriety
of any investment in the debt securities.

    The trustee  currently  provides trustee services to our subsidiaries in the
ordinary course of business under other indentures. The trustee does not provide
commercial banking services to us or our subsidiaries.

Consolidation, Merger, Conveyance or Transfer

    We will not consolidate with or merge into any other corporation, or convey,
transfer or lease all or  substantially  all of our properties and assets to any
individual or organization, unless:

    o    the  surviving or  transferee  entity is a  corporation  organized  and
         existing  under  the  laws of the  United  States  or any  state or the
         District  of  Columbia,   and  expressly  assumes,  by  a  supplemental
         indenture,  all of the  obligations  of the company under the indenture
         and the securities;

    o    no event of default and no event  which,  after notice or lapse of time
         or both, exists at the time of the proposed  transaction or would occur
         as a result of the transaction; and

    o    the  company  provides  the  trustee an  Officers'  Certificate  and an
         Opinion of Counsel to the effect that the transaction complies with all
         applicable provisions of the indenture.

    When our successor  assumes our obligations under the indenture and the debt
securities,  and  when  any  other  conditions  required  by the  indenture  are
satisfied,  the successor  will succeed to and be  substituted  for us under the
indenture.

Modification; Supplemental Indentures

    The  indenture  provides  that  the  company  and the trustee may enter into
supplemental  indentures  without the  consent of any holders for the  following
purposes:

    o    to reflect a merger,  transfer of assets or similar transaction and the
         assumption of our obligations under the indenture and the securities by
         the surviving or transferee entity;

    o    to add  provisions  for the benefit of holders of one or more series of
         securities;


                                       13



    o    to add additional events of default under the securities;

    o    to add or  change  provisions  needed to  facilitate  the  issuance  of
         securities as certificated or global securities;

    o    to provide collateral as security for repayment of the securities;

    o    to establish the forms or terms of  securities  as permitted  under the
         indenture;

    o    to  reflect  appointment  of  a  successor  trustee  or  to  facilitate
         administration of the indenture by more than one trustee; and

    o    to cure any ambiguity or inconsistency  in the indenture;  provided the
         change  does not  adversely  affect  the  interests  of  holders of the
         securities in any material respect.

    We and the trustee may modify or amend the terms of the  indenture  with the
consent of the holders of not less than a majority in aggregate principal amount
of the  outstanding  debt  securities of each affected  series and a majority in
aggregate  principal  amount of the outstanding  debt securities of all affected
series.  However,  without the consent of each holder of all of the  outstanding
debt securities affected by that modification, we may not:

    o    change the date  stated on the debt  security  on which any  payment of
         principal or interest is stated to be due; reduce the principal  amount
         or any premium or interest on, any debt security, including in the case
         of a discounted debt security,  the amount payable upon acceleration of
         the  maturity  thereof;  change  the place of payment  or  currency  of
         payment of principal  of, or premium,  if any, or interest on, any debt
         security;  or impair the right to bring suit to enforce  any payment on
         or with respect to any debt security after the stated  maturity (or, in
         the case of redemption, on or after the redemption date); or;

    o    reduce  the  percentage  in  principal   amount  of  outstanding   debt
         securities  of any  series  which  must  consent in order to effect any
         modification  or amendment of the  indenture,  any waiver of compliance
         with any  provisions of the  indenture or any waiver of defaults  under
         the indenture; or

    o    modify any provisions relating to holder consent to amendments,  except
         to increase the percentage of holders  required to approve an amendment
         or to  prohibit  any  amendment  without the  approval of all  affected
         holders.

Covenants

    We undertake certain agreements or commitments,  including  agreements to do
the following:

    o    punctually make payments on the debt securities;

    o    maintain one or more offices at which debt  securities can be presented
         for payment and registration;

    o    act as, or  appoint  a third  party  as,  paying  agent for one or more
         series of the securities;

    o    hold  the  trustee  harmless  from any  loss or  claim  arising  out of
         activities of the paying agent;

    o    provide  the  paying  agent  with  sufficient  funds  to make  required
         payments when due under the securities;

    o    give the  trustee  written  notice  of any event of  default  under the
         indenture within 30 days of its occurrence;

    o    maintain our properties in good condition, subject to ordinary wear and
         tear;

    o    file all  required  tax  returns and pay taxes,  assessments  and other
         governmental charges as they become due and payable; and


                                       14


    o    maintain  our  corporate   existence  and  all  rights  and  franchises
         necessary for the operation of our business.

    Unless a prospectus supplement or term sheet provides differently, there are
no provisions  which limit our ability to incur debt or which protect holders of
debt  securities  if  we  were  to  engage  in a  highly  leveraged  or  similar
transaction or in the event of a change in control of the company.

Redemption

     The indenture  has  provisions  for  redemption of any series of securities
that is  redeemable  before its stated  maturity  date.  If we elect to redeem a
series,  we will give the  trustee  at least 60 days'  notice.  If less than all
securities  of like  tenor are to be  redeemed,  the  trustee  shall  select the
securities  to be redeemed in a manner the trustee  deems fair and  appropriate.
The  company or the  trustee  must give  holders of  securities  to be  redeemed
written notice of certain items  required  under the  indenture,  by first class
mail not less  than 30 and not more than 60 days  before  the  redemption  date.
After notice of  redemption is given,  the  securities  selected for  redemption
become due and payable,  and cease to bear  interest,  on the  redemption  date,
except  that if the  company  fails  to make  the  required  payment  to  redeem
securities  selected for  redemption,  those  securities  shall continue to bear
interest  until paid. If securities are redeemed only in part, the company will,
upon  surrender  of the  security  and at no charge to the holder,  issue to the
holder  a  like  security  for  the  unredeemed   portion  of  the  security  so
surrendered.

    If  a  series  of  securities  is  redeemable,   the  applicable  prospectus
supplement or term sheet will disclose that fact.

    If we plan to redeem the debt securities,  before the redemption  occurs, we
are not required to:

    o    issue,  register the transfer of, or exchange any debt security of that
         series during the period beginning 15 days before we mail the notice of
         redemption and ending on the day we mail the notice; or

    o    after we mail the notice of  redemption,  register  the  transfer of or
         exchange any debt security  selected for redemption,  except, if we are
         only redeeming a part of a debt  security,  we are required to register
         the transfer of or exchange the unredeemed portion of the debt security
         if the holder requests.

Sinking Funds

     One or more series of the  securities may provide for mandatory or optional
sinking fund payments for the retirement of a series of securities.  The company
may satisfy  sinking fund payment  obligations by delivering  securities of such
series previously  redeemed from the holders and not previously  credited toward
sinking fund payment obligations.  The company must give the trustee at least 60
days' notice of the portion of a sinking fund payment that is to be satisfied by
payment  in cash and the  portion  that is to be  satisfied  by  delivering  and
crediting securities.

Defeasance of Debt Securities

    Unless otherwise  provided in the prospectus  supplement or term sheet for a
series  of debt  securities,  the  company  may be  discharged  from any and all
obligations  with respect to any debt  securities  or series of debt  securities
(except for certain  obligations  to register  the  transfer or exchange of debt
securities, to replace debt securities if stolen, lost or mutilated, to maintain
paying  agencies  and to hold money for  payment in trust) on and after the date
the  conditions  set forth in the  indenture  are  satisfied.  These  conditions
include the deposit with the trustee, in trust for this purpose, of money and/or
U.S.  government  obligations,  which through the scheduled payment of principal
and  interest in respect  thereof in  accordance  with their terms will  provide
money in an  amount  sufficient  to pay the  principal  of and any  premium  and
interest on the debt securities on the stated maturity date of these payments or
upon  redemption,  as the  case may be,  in  accordance  with  the  terms of the
indenture and the debt securities.

    The company  must  deliver to the trustee an opinion of counsel  that either
the proposed defeasance  qualifies as a reorganization under federal tax law and
the debt securities  defeased  qualify as securities for the purposes of Section
354 of the Internal Revenue Code, as amended,  or the defeasance will not result
in income tax  liability  to the trustee or the  holders of the debt  securities
defeased as a result of a deemed  exchange  under Treasury  Regulations  Section
1.1001-3 or any successor regulation.



                                       15


                         DESCRIPTION OF PREFERRED STOCK


    The  following is a summary of the terms of the shares of  preferred  stock.
Our charter  and by-laws  contain  the full terms of the  preferred  stock.  You
should  read these  documents  carefully  to fully  understand  the terms of the
shares of preferred stock.


Shares Authorized and Shares Outstanding

    As of the date of this  prospectus,  we had  380,000  shares  of  authorized
preferred  stock, of which 139,000 shares  designated as 4.4% Series C Preferred
Stock, $25 par value, were issued and outstanding.  The remaining 241,000 shares
of our  preferred  stock are not issued and  outstanding  as of the date of this
prospectus.  However,  certain shares have been designated for possible issuance
as Series D as explained below (see "Series D Participating Preferred Stock").


    Under Delaware law, we may issue the undesignated  shares of preferred stock
from time to time in up to eight series without stockholder approval. Subject to
limitations prescribed by Delaware law and our charter and by-laws, our board of
directors  can  determine  the  number of  shares  constituting  each  series of
preferred stock and the designation, preferences, voting powers, qualifications,
and special or relative  rights or privileges of that series.  These may include
provisions  as  may  be  desired  concerning  voting,   redemption,   dividends,
dissolution,  or the distribution of assets,  conversion or exchange,  and other
subjects or matters as may be fixed by  resolution of the board or an authorized
committee of the board.  Delaware law provides that any determination that would
have the effect of  altering  or changing  the  powers,  preferences  or special
rights of holders of shares of Series C Preferred Stock may be adopted only with
the approval of holders of a majority of the  outstanding  Series C shares.  The
preferred  stock that may be offered by this prospectus  will,  when issued,  be
fully paid and nonassessable and will not have, or be subject to, any preemptive
or similar rights.


    If we offer a specific series of preferred stock under this  prospectus,  we
will describe the terms of the preferred  stock in the prospectus  supplement or
term sheet for that  offering and will file a copy of the document  establishing
the terms of the preferred stock with the SEC. The description will include:

    o    the title, series designation and stated value;

    o    the number of shares offered, the liquidation  preference per share and
         the purchase price;

    o    the dividend rate(s), period(s) and/or payment date(s), or method(s) of
         calculation for dividends;

    o    whether   dividends  will  be  cumulative,   partially   cumulative  or
         non-cumulative  and, if  cumulative or partially  cumulative,  the date
         from which the dividends will accumulate;

    o    the procedures for any auction or remarketing, if any;

    o    the provisions for a sinking fund, if any;

    o    the provisions for redemption, if applicable;

    o    any  listing  of the  preferred  stock on any  securities  exchange  or
         market;

    o    whether the preferred stock will be convertible  into any series of our
         common stock, and, if applicable,  the conversion price (or how it will
         be calculated);

    o    voting rights, if any, of the preferred stock;

    o    whether  interests  in the  preferred  stock  will  be  represented  by
         depositary shares;

    o    a discussion of any material  and/or  special U.S.  federal  income tax
         considerations applicable to the preferred stock;

                                       16


    o    the  relative  ranking and  preferences  of the  preferred  stock as to
         dividend rights and rights upon liquidation,  dissolution or winding up
         of our affairs;

    o    any  limitations on issuance of any class or series of preferred  stock
         ranking senior to or on parity with the series of preferred stock as to
         dividend rights and rights upon our liquidation, dissolution or winding
         up;

    o    any  other  specific  terms,   preferences,   rights,   limitations  or
         restrictions of the preferred stock; and

    o    any transfer agent for the preferred stock.

    Unless we specify otherwise in the applicable  prospectus supplement or term
sheet, any future issuance of preferred  stock,  with respect to dividend rights
and  rights  upon our  liquidation,  dissolution  or  winding  up,  will rank as
follows:

    o    senior to all classes or series of our common stock,  and to all equity
         securities  issued by us the terms of which  specifically  provide that
         they rank junior to the  preferred  stock with respect to those rights;
         and

    o    on a parity with all equity securities we issue that do not rank senior
         or junior to the preferred stock with respect to those rights.

    As used for these purposes,  the term "equity  securities"  does not include
convertible debt securities.

Global Securities


    If we  decide  to issue  preferred  stock in the form of one or more  global
securities,  then we will  register  the  global  securities  in the name of the
depositary for the global  securities or the nominee of the depositary,  and the
global  securities will be delivered by the trustee to the depositary for credit
to the accounts of the holders of beneficial  interests in the global  preferred
stock. The prospectus  supplement or term sheet will describe the specific terms
of the depositary  arrangement for preferred stock of a series that is issued in
global  form.  The  company,  the  trustee,  any payment  agent and the security
registrar will have no responsibility or liability for any aspect of the records
relating to or payments  made on account of  beneficial  ownership  interests in
global preferred stock or for maintaining,  supervising or reviewing any records
relating to these beneficial ownership interests.


Series C Preferred Stock


    Dividends on the outstanding  Series C Preferred Stock are payable quarterly
before any dividends  can be paid on common stock.  Each share is entitled to 16
votes and is voted  along with the  common  shares,  with the right to  cumulate
votes at any election of directors (see "Description of Common Stock" below). At
our option,  these shares may be wholly or partly redeemed at a redemption price
of  $26.75  per  share  together  with  accrued  dividends.  Upon any  voluntary
dissolution  or  liquidation  of the  company,  holders of these  shares will be
entitled  to  receive a  liquidation  amount of $26.75 per share  together  with
accrued  dividends.  Upon any  involuntary  dissolution  or  liquidation  of the
company the holders of the Series C Preferred  Stock will be entitled to receive
$25.00 per share  together with accrued  dividends.  After these payments to the
holders of Series C  Preferred  Stock and after any  payments  to holders of any
other  series  of  preferred  stock  which we may issue in the  future,  we will
distribute our remaining net assets to holders of the common shares.  The number
of shares of the Series C Preferred  Stock may be  increased or decreased by the
board.


Series D Participating Preferred Stock


    In January  1998,  the  company's  board  adopted a  resolution  designating
221,000 shares of preferred stock as Series D Participating Preferred Stock. The
number  of shares  may be  increased  or  decreased  by the  board  prior to the
issuance of any shares of this series.


    No  Series  D shares  have  been  issued.  These  shares  are  related  to a
Stockholder  Rights  Plan and would be issued if the rights were  triggered.  If
triggered,  each  right  would be  converted  into the  right  to  purchase  one
one-hundredth of a share of the Series D Preferred  Stock.  Until the rights are
triggered  each common share  outstanding on and after January

                                       17


28, 1998  includes  one right,  which is  evidenced  solely by the common  stock
certificate.  For a  description  of the rights and the  rights  agreement,  see
"Rights Agreement" below.


    Subject  to the  rights  and the  holders  of any  shares  of any  series of
preferred  stock (or any similar stock) ranking prior and superior to the Series
D Preferred  Stock with respect to dividends,  the holders of shares of Series D
Preferred  Stock,  in preference to the holders of common stock and of any other
junior  stock,  will be entitled to receive,  as and when declared by the board,
dividends  payable in cash on the same date as dividends on the company's Series
C Preferred Stock. Each share of Series D Preferred Stock will receive dividends
(subject  to certain  adjustments)  equal to 100 times the  aggregate  per share
amount (payable in kind) of all non-cash dividends or other distributions, other
than a dividend  payable in the company's  common stock,  declared on the common
stock.  We will be required to pay any of these  dividends  that are accrued and
unpaid, without interest, before we may pay any dividends on common shares.


    If we declare or pay any dividend on common stock  payable in common  stock,
or split,  combine or consolidate  outstanding common stock (by means other than
by payment of a dividend  in common  stock)  into a greater or lesser  number of
shares,  then the amount to which Series D Preferred  stockholders were entitled
immediately  prior to that  event  will be  adjusted.  The  adjustment  would be
determined by multiplying  that amount by a fraction,  of which the numerator is
the number of common shares  outstanding  after the event and the denominator is
the number of common shares outstanding prior to the event.

    We will then  declare a dividend or  distribution  on the Series D Preferred
Stock  immediately  after we declare the dividend or  distribution on the common
stock (other than a dividend payable in common stock).  A similar  adjustment in
the voting power of each share of Series D Preferred  Stock will be made,  which
normally  carry  100  votes  per  share on all  matters  submitted  to a vote of
stockholders,  voting along with the common stock unless  otherwise  provided in
our charter or by law.


    If the company is liquidated,  dissolved or wound up, no distribution  shall
be made to the holders of shares of stock ranking junior (either as to dividends
or upon liquidation,  dissolution or winding up) to the Series D Preferred Stock
until the holders of shares of Series D Preferred  Stock have received a minimum
of $100.00 per share, plus all accrued and unpaid dividends and distributions on
the Series D Preferred  Stock.  In any event,  the holders of Series D Preferred
Stock will be entitled to receive an amount per share  (subject to adjustment as
discussed  below) equal to 100 times the amount to be  distributed  per share to
holders of common  stock.  Distributions  to the  holders of stock  ranking on a
parity (either as to dividends or upon  liquidation,  dissolution or winding up)
with the  Series D  Preferred  Stock  will be made on a pro rata  basis with the
Series D Preferred Stock.


    If we declare or pay any  dividend  on the  common  stock  payable in common
stock,  subdivide,  combine or consolidate common stock (by  reclassification or
otherwise  than by  payment  of a dividend  in common  stock)  into a greater or
lesser number of shares, then the aggregate amount to which holders of shares of
Series D Preferred Stock were entitled  immediately prior to any of those events
upon  liquidation,  dissolution or winding up will be adjusted so that the ratio
of liquidation  preference due per share of Series D Preferred Stock will be the
same both before and after the event and that these  payments will be made prior
to any payments to securities which rank junior to the Series D Preferred Stock.

    If we enter into any consolidation, merger, combination or other transaction
in which our  common  stock is  exchanged  for or changed  into  other  stock or
securities,  cash  and/or any other  property,  each share of Series D Preferred
Stock  will have a right to receive  100 times the  aggregate  consideration  to
which each common share is entitled.

    Adjustments will be made to the  consideration  which the Series D Preferred
Stock is entitled to receive in the event we declare or pay any  dividend on the
common stock payable in our common stock,  or subdivide,  combine or consolidate
our common stock (by reclassification or otherwise than by payment of a dividend
in our common stock into a greater or lesser number) so as to prevent dilution.

    Some or all of the Series D Preferred Stock may be redeemed at our option on
any dividend payment date at a redemption price per share equal to 100 times the
fair market value of a common share on that date,  together with all accrued and
unpaid dividends on the Series D Preferred Stock.

                                       18


    The Series D  Preferred  Stock ranks on a parity with the Series C Preferred
Stock with  respect to  dividends,  and junior to all other  series of preferred
stock with respect to the distribution of assets.

    Our  certificate  of  incorporation  may not be amended in any manner  which
would  materially  alter or change the powers,  preferences or special rights of
the  Series D  Preferred  Stock  so as to  affect  them  adversely  without  the
affirmative vote of the holders of at least a majority of the outstanding shares
of Series D Preferred  Stock,  voting together as a single class, in addition to
any other vote of stockholders required by law.

                           DESCRIPTION OF COMMON STOCK


    Our certificate of incorporation authorizes the issuance of up to 25,000,000
common shares,  par value $0.01 per share.  There were 15,182,046  shares of the
company's common stock issued and outstanding as of May 5, 2003. As of March 31,
2003,  our officers held options  covering  154,500 common shares which they had
not yet  exercised.  The  approximate  number of  stockholders  of record of our
common stock as of May 5, 2003 was 4,500.  The company's  common stock is listed
on the New York  Stock  Exchange  under the  symbol  "CWT." We will apply to the
Exchange  to  list  any  common  stock  issued  under  this  prospectus  and any
supplement or term sheet.


    Holders  of our  common  stock  are  entitled  to vote at all  elections  of
directors  and to vote or consent on all  questions  at the rate of one vote for
each share.  The holders of the Series C Preferred Stock vote along with holders
of the common  stock.  Shareholders  may vote  cumulatively  in the  election of
directors.  Under cumulative voting, every stockholder entitled to vote may give
one  candidate a number of votes equal to the number of  directors to be elected
multiplied  by the number of shares held.  Or, the  stockholder  may  distribute
these votes on the same principle  among as many  candidates as the  stockholder
desires. Because each share of Series C Preferred Stock is entitled to 16 votes,
preferred  stockholders  may  cumulate  16 votes for each share  owned times the
number of directors to be elected.


    Subject to the rights, privileges, preferences,  restrictions and conditions
attaching  to any other  class or series of shares of the  company,  holders  of
common  stock have the right to receive any  dividends we declare and pay on our
common stock. They also have the right to receive our remaining assets and funds
upon liquidation, dissolution or winding-up, if any, after we pay to the holders
of the Series C Preferred Stock and the holders of any other series of preferred
stock  the  amounts  they are  entitled  to,  and after we pay all our debts and
liabilities.


    Our common stock is subject and  subordinate  to any rights and  preferences
granted under our  Certificate of  Incorporation  and any rights and preferences
which may be granted to any series of preferred  stock by our board  pursuant to
the authority conferred upon our board under the Certificate of Incorporation.

    After all  cumulative  dividends  are  declared and paid or set apart on the
Series C Preferred Stock and on any other series of preferred stock which may be
outstanding,  the board may declare any additional dividends on our common stock
out of the surplus or net profits as in their discretion may seem proper. During
2002, we paid dividends on the Series C Preferred Stock totaling $153,000.

    The  common  stock  issued by this  prospectus  and any  related  prospectus
supplement or term sheet will, when issued,  be fully paid and nonassessable and
will not have, or be subject to, any preemptive or similar rights.

    EquiServe,  L.P. is the transfer agent,  registrar and dividend paying agent
for our common stock. Its phone number is (800) 736-3001.

                                       19


                                RIGHTS AGREEMENT


    Simultaneously  with the resolution  approving the Series D Preferred Stock,
our board of directors declared a dividend of one preferred share purchase right
for  each  outstanding  share of our  common  stock.  Each  right  entitles  the
registered holder to purchase from us one one-hundredth of a share of the Series
D  Preferred  Stock at a price of $120.00 per one  one-hundredth  of a preferred
share, subject to certain  adjustments.  The description and terms of the rights
are set forth in a Rights Agreement between us and Bank Boston,  N.A., as rights
agent,  dated as of February  12, 1998 which is on file with the SEC. You should
carefully read the Rights Agreement to understand its terms and conditions.


    Initially, the rights will be attached to all certificates  representing our
common stock then outstanding,  regardless of whether any of these  certificates
has a copy of a Summary  of  Rights  attached  thereto,  and no  separate  right
certificates will be distributed. The rights will separate from the common stock
and a "Distribution  Date" will occur upon the acquisition of 15% or more of our
common  stock by a third party or a third  party's  announcement  of a tender or
exchange  offer for 15% or more of our common  stock.  At present we have no 15%
holders of our common stock to our knowledge.


    The Rights Agreement  provides that, until the Distribution Date, the rights
will be  transferred  with and only with the company's  common stock.  Until the
Distribution  Date (or earlier  redemption  or  expiration  of the rights),  new
common  share  certificates  issued  after the Record Date upon  transfer or new
issuance  of common  stock  will  contain a  notation  incorporating  the Rights
Agreement by reference.  Until the Distribution  Date (or earlier  redemption or
expiration of the rights),  the surrender for transfer of any  certificates  for
common stock outstanding as of the Record Date will also constitute the transfer
of the rights  associated with the common stock represented by that certificate.
As soon as practicable  following the Distribution Date,  separate  certificates
evidencing the rights will be mailed to holders of record of the common stock as
of the close of  business on the  Distribution  Date and these  separate  rights
certificates alone will evidence the rights.


    The rights are not exercisable until the Distribution  Date. The rights will
expire on February 11, 2008,  unless earlier redeemed or exchanged by us in each
case as described  below.  Until a right is  exercised,  the holder will have no
rights as a stockholder,  including, without limitation, the right to vote or to
receive dividends.

    The  purchase  price  payable  and the number of  Preferred  Shares or other
securities  or  property  issuable  upon  exercise  of the rights are subject to
adjustment  from  time to time to  prevent  dilution  from any of the  following
events:

    (i)     a   stock   dividend   on,   or  a   subdivision,   combination   or
            reclassification of the Preferred Shares,

    (ii)    the grant to holders of the  Preferred  Shares of certain  rights or
            warrants to subscribe for Preferred Shares or convertible securities
            at less than the current market price of the Preferred Shares, or

    (iii)   thedistribution  to holders of the Preferred  Shares of evidences of
            indebtedness or assets  (excluding  regular  periodic cash dividends
            out of  earnings  or  retained  earnings  or  dividends  payable  in
            Preferred Shares) or of subscription  rights or warrants (other than
            those referred to above).

    The number of outstanding  rights  associated  with each share of our common
stock is also subject to  adjustment in the event of a stock split of the common
stock or a stock  dividend on the common  stock  payable in common  stock or any
subdivisions, consolidations or combinations of the common stock if any of these
events occur prior to the Distribution Date.

    With  certain  exceptions,  no  adjustment  in the  purchase  price  will be
required until  cumulative  adjustments  require an adjustment of at least 1% in
the  purchase  price.  No  fractional  preferred  or common stock will be issued
(other than  fractions of Preferred  Shares which are integral  multiples of one
one-hundredth of a Preferred Share, which may, at our election,  be evidenced by
depositary  receipts) and in lieu thereof,  a payment in cash will be made based
on the market  price of the  Preferred  or common stock on the last trading date
prior to the date of exercise.


    In the  event  that any  person  or group  becomes  an  Acquiring  Person (a
"Trigger Event"), each holder of a right, other than the Acquiring Person (whose
rights will thereafter be void),  will thereafter have the right to receive upon
exercise  at its then  current  exercise  price that  number of shares of common
stock (or, in the event there are  insufficient  shares


                                       20



authorized,  substitute consideration such as cash, property or other securities
of the company, such as Preferred Shares) having a market value of two times the
purchase price of the right.

    In the event that,  after a person or group has become an Acquiring  Person,
the company is acquired in a merger or other business combination transaction or
50% or more of its consolidated assets or earning power are sold, each holder of
a right  (other than an  Acquiring  Person,  whose rights will become void) will
thereafter have the right to receive, upon the exercise of the right at its then
current  exercise price,  that number of shares



of common stock of the  acquiring  person having a market value of two times the
exercise price of the right.

    At any time  until ten days  following  a Trigger  Event,  we may redeem the
rights in whole,  but not in part,  at a price of $.001 per  right.  Immediately
upon the action of the board of directors ordering redemption of the rights, the
right to exercise the rights will terminate and the only right of the holders of
rights will be to receive the redemption price.

    After the rights are  triggered,  our board may exchange  some or all of the
rights for common or preferred stock at a one-for-one  exchange ratio. The board
will not exchange the rights after any Acquiring  Person  becomes the Beneficial
Owner of 50% or more of our outstanding common stock.

    As long as the rights are redeemable, we may amend the rights in any manner.
After the rights are no longer redeemable, we may amend the rights in any manner
that does not adversely affect the interests of holders of the rights.

    Because of the nature of the Preferred  Shares'  dividend,  liquidation  and
voting  rights,  the  value  of  the  one  one-hundredth  of a  Preferred  Share
purchasable  upon  exercise of each right  should  approximate  the value of one
share of our common stock.


    The Rights Agreement between the company and the rights agent specifying the
terms of the rights and includes as Exhibit B the form of rights  certificate is
incorporated into the registration statement of which this prospectus is a part.
The foregoing description of the rights and the Rights Agreement is qualified in
its entirety by reference to the Rights Agreement.



                                       21


            ANTI-TAKEOVER EFFECTS OF OUR CERTIFICATE OF INCORPORATION
                           AND BYLAWS AND DELAWARE LAW

    Our bylaws contain  provisions  requiring advance written notice of director
nominations or other  proposals by  stockholders  and requiring  directors to be
free of certain  affiliations  with certain of our  competitors.  Also,  we have
adopted  severance  arrangements  with  executive  officers  as  part  of  their
compensation  packages. We believe that severance arrangements do not discourage
a takeover attempt, since they merely provide benefits to executives as a result
of  a  change  in  control.   Also,  under  our  certificate  of  incorporation,
stockholders may not act by written consent,  and all stockholder action must be
taken at a properly called and noticed meeting of stockholders.


    The company is subject to Section 203 of the  Delaware  General  Corporation
Law, which provides,  with certain exceptions,  that a Delaware  corporation may
not  engage in  certain  business  combinations  with a person or  affiliate  or
associate  of such  person who is an  "interested  stockholder"  for a period of
three years from the date such person became an interested stockholder unless:


    o    the  transaction  resulting  in  the  acquiring  person's  becoming  an
         interested stockholder, or the business combination, is approved by the
         board of  directors  of the  corporation  before the person  becomes an
         interested stockholder;

    o    the  interested  stockholder  owned at least 85% of the voting stock of
         the  corporation  outstanding  at the time the  transaction  commenced,
         excluding for purposes of determining the voting stock outstanding (but
         not the outstanding  voting stock owned by the interested  stockholder)
         those share owned

    o    by persons who are directors and also officers, and

    o    employee  stock plans in which  employee  participants  do not have the
         right to determine  confidentially  whether  shares held subject to the
         plan will be tendered in a tender or exchange offer; or

    o    on or after the date the person becomes an interested stockholder,  the
         business   combination  is  approved  by  the  corporation's  board  of
         directors  and by the holders of at least 66 2/3% of the  corporation's
         outstanding  voting  stock at an annual or special  meeting,  excluding
         shares owned by the interested stockholder.

An  "interested  stockholder"  is defined as any person that is (x) the owner of
15% or  more  of the  outstanding  voting  stock  of the  corporation  or (y) an
affiliate or associate  of the  corporation  and was the owner of 15% or more of
the  outstanding  voting  stock  at  any  time  within  the  three  year  period
immediately  prior to the date on which it sought to be determined  whether such
person is an interested stockholder.

                              PLAN OF DISTRIBUTION

    We may sell the securities through one or more of the following ways:

    o    directly to purchasers;

    o    to or through one or more underwriters or dealers; or

    o    through agents.

    A prospectus  supplement or term sheet with respect to a particular issuance
of  securities  will set forth the terms of the  offering  of those  securities,
including the following:

    o    name or names of any underwriters, dealers or agents;

    o    the purchase price of the  securities  and the estimate  amount we will
         receive;

    o    underwriting discounts and commissions; and

                                       22


    o    any initial  public  offering  price and any  discounts or  concessions
         allowed or reallowed or paid to dealers.

    If we use  underwriters  in the sale,  the  underwriters  will  acquire  the
securities  for their own  account and they may resell them from time to time in
one or more transactions,  including negotiated transactions,  at a fixed public
offering price or at varying prices determined at the time of sale. Underwriting
syndicates  represented  by one or  more  managing  underwriters  or one or more
independent firms acting as underwriters may offer the securities to the public.
In connection with the sale of securities, we may compensate the underwriters in
the  form of  underwriting  discounts  or  commissions.  The  purchasers  of the
securities  for  whom  the  underwriters  may act as  agent  may  also  pay them
commissions.  Underwriters  may sell the securities to or through  dealers,  and
these dealers may receive compensation in the form of discounts,  concessions or
commissions  from the  underwriters  and/or  commissions from the purchasers for
whom  they may act as  agents.  Unless  otherwise  set  forth in the  applicable
prospectus  supplement or term sheet,  the  obligations of any  underwriters  to
purchase  the  securities  will be  subject  to  conditions  precedent,  and the
underwriters  will be  obligated to purchase  all of the  securities  if any are
purchased.

    If we use dealers in the sale of the securities, we will sell the securities
to the dealers as principals.  The dealers may then resell the securities to the
public at varying  prices to be  determined by the dealer at the time of resale.
The applicable prospectus supplement or term sheet will name any dealer, who may
be deemed to be an  underwriter,  as that term is defined in the Securities Act,
involved in the offer or sale of  securities,  and set forth any  commissions or
discounts we grant to the dealer.

    If we use agents in the sales of the  securities,  the  agents  may  solicit
offers to purchase the securities  from time to time.  Any of these agents,  who
may be deemed to be an  underwriter,  as that term is defined in the  Securities
Act,  involved  in the offer or sale of the  securities  will be named,  and any
commissions payable by us to such agent set forth, in the applicable  prospectus
supplement or term sheet. Any agent will be acting on a reasonable efforts basis
for the period of its appointment or, if indicated in the applicable  prospectus
supplement or term sheet, on a firm commitment basis.

    We may also sell securities  directly to  institutional  investors or others
who may be deemed to be  underwriters  within the meaning of the  Securities Act
with  respect to resales.  The terms of those sales  would be  described  in the
prospectus supplement or term sheet.

    If the prospectus  supplement or term sheet so indicates,  we will authorize
agents, underwriters or dealers to solicit offers to purchase securities from us
at the public  offering  price set forth in the  prospectus  supplement  or term
sheet pursuant to stock  purchase or delayed  delivery  contracts  providing for
payment and delivery on a specified  date in the future.  The contracts  will be
subject only to those conditions set forth in the prospectus  supplement or term
sheet, and the prospectus supplement or term sheet will set forth the commission
payable for solicitation of the contracts.

    We may engage in  at-the-market  offerings of our common  stock.  An "at the
market"  offering is an offering of our common stock at other than a fixed price
on or  through  the  facilities  of the New  York  Stock  Exchange.  Under  Rule
415(a)(4) under the Securities  Act, the total value of at the market  offerings
made under this  prospectus may not exceed 10% of the aggregate  market value of
our common stock held by persons who are not our  affiliates on a date within 60
days prior to filing the  registration  statement  containing  this  prospectus.
Accordingly,  as of the  date of this  prospectus,  we may not sell  under  this
prospectus  more  than   approximately   $36,000,000  of  our  common  stock  in
at-the-market  offerings.  Any underwriter  that we engage for an  at-the-market
offering will be named in the prospectus  supplement.  Additional details of our
arrangement with the underwriter,  including  commissions or fees paid by us and
whether the  underwriter  is acting as principal or agent,  will be described in
the related prospectus supplement or term sheet.

    Agents, dealers and underwriters may be entitled under agreements with us to
indemnification against some civil liabilities,  including liabilities under the
Securities  Act, or to  contribution  with respect to payments which the agents,
dealers  or  underwriters  may  be  required  to  make.   Agents,   dealers  and
underwriters  or their  affiliates may engage in  transactions  with, or perform
services for, us or our subsidiaries for customary compensation.

    If indicated in the applicable  prospectus  supplement or term sheet, one or
more firms may offer and sell securities in connection  with a remarketing  upon
their purchase,  in accordance with their terms,  acting as principals for their
own accounts or as our agents.  Any remarketing  firm will be identified and the
terms of its  agreement,  if any,  with us will be

                                       23


described  in the  applicable  prospectus  supplement  or term sheet.  We may be
obligated to indemnify the remarketing firm against some liabilities,  including
liabilities  under the Securities  Act, and the  remarketing  firm may engage in
transactions  with or perform  services for us or our subsidiaries for customary
compensation.

    Any  underwriter  may engage in  over-allotment,  stabilizing  and syndicate
short covering  transactions  and penalty bids in accordance  with  Regulation M
under the Securities Exchange Act of 1934, as amended.  Over-allotment  involves
sales  in  excess  of  the  offering  size,  which  creates  a  short  position.
Stabilizing  transactions  involve bids to purchase the  underlying  security so
long as the stabilizing bids do not exceed a specified maximum.  Syndicate short
covering  transactions  involve purchases of securities in the open market after
the distribution has been completed in order to cover syndicate short positions.
Penalty bids permit the underwriters to reclaim selling concessions from dealers
when the  securities  originally  sold by the dealers are  purchased in covering
transactions to cover syndicate short  positions.  These  transactions may cause
the price of the  securities  sold in an  offering  to be  higher  than it would
otherwise be. These  transactions,  if  commenced,  may be  discontinued  by the
underwriters at any time.

    Any  securities,  other  than  our  common  stock,  will be a new  issue  of
securities with no established  trading market.  We cannot assure you that there
will be a market for the  securities of any  particular  security,  or that if a
market  does  develop,  that  it will  continue  to  provide  holders  of  those
securities with liquidity for their investment or will continue for the duration
the securities are outstanding.

    The  prospectus  supplement or term sheet relating to each offering will set
forth the anticipated date of delivery of the securities.

                                  LEGAL MATTERS

    Bingham McCutchen LLP, San Francisco,  California will issue a legal opinion
for us with respect to the validity of the  securities.  Certain  legal  matters
will be  passed  upon for the  underwriters  by  Chapman  and  Cutler,  Chicago,
Illinois.

                                     EXPERTS


    The  consolidated  financial  statements  and schedule of  California  Water
Service  Group as of December 31, 2002 and 2001 and for each of the years in the
three-year  period ended December 31, 2002, have been  incorporated by reference
herein and in the  registration  statement in reliance  upon the reports of KPMG
LLP,  independent  accountants,  incorporated by reference herein,  and upon the
authority of said firm as experts in accounting and auditing.


                       WHERE YOU CAN FIND MORE INFORMATION


    The company has filed with the SEC a registration statement on Form S-3 with
respect to the  securities to be offered by this  prospectus  and any prospectus
supplement  or term sheet.  This  prospectus  omits  certain of the  information
contained  in the  registration  statement  and its  exhibits.  This  prospectus
discusses material  provisions of the form of indenture we propose to enter into
with U.S Bank  National  Association  as trustee for debt  securities to be sold
under this prospectus and any prospectus  supplement or term sheet.  Because the
prospectus may not contain all the information that you may find important,  you
should  review  the full  text of the  indenture  and  other  documents  we have
incorporated by reference into the registration statement.

    The registration statement,  including exhibits thereto, may be inspected at
the Public Reference facility  maintained by the Commission at 450 Fifth Street,
N.W., Washington, D.C. 20549. The public may obtain information on the operation
of the Public  Reference Room by calling the Commission at  1-800-SEC-0330.  The
registration  statement  and other  information  filed with the  Commission  are
available at the web site  maintained by the Commission on the world wide web at
http://www.sec.gov.  Investors may access our SEC filings  through the company's
website at http://www.calwater.com.


    The SEC allows us to  "incorporate  by reference"  information  that we file
with the SEC, which means that we can disclose  important  information to you by
referring you to those documents.  The information  incorporated by reference is
considered to be part of this  prospectus,  and later  information  that we file
with the SEC will  automatically  update  and  supersede  this  information.  We
incorporate by reference the documents listed below:

                                       24


     1)  Our Annual  Report on Form 10-K for the fiscal year ended  December 31,
         2002;

     2)  Our Quarterly Report on Form 10-Q for the quarter ended March 31, 2003;


     3)  The  description  of our  common  stock set  forth in the  registration
         statement  on Form 8-A under  Section  12(b) of the  Exchange Act filed
         March 18, 1994 and any future amendment or report filed for the purpose
         of updating that description; and

     4)  The   description  of  our  Preferred  Stock  Purchase  Rights  in  the
         registration  statement on Form 8-A under Section 12(b) of the Exchange
         Act filed  February  13, 1998 and any future  amendment or report filed
         for the purpose of updating that description.

    All documents we file with the Commission  after the date of this prospectus
under  Sections  13(a),  13(c),  14 and 15(d) of the Exchange Act, and before we
file a  post-effective  amendment  which reports that all securities  offered in
this prospectus have been sold, or to deregister all unsold securities, are also
incorporated  by reference and will be part of this prospectus from the dates we
file each of those documents.

    You may  request  a copy  of  these  filings,  at no  cost,  by  writing  or
telephoning us at the following address:


    California Water Service Group
    1720 North First Street
    San Jose, CA 95112-4598
    Attn: Investor Relations
    Phone: (408) 367-8200


    You  should  rely  only on the  information  incorporated  by  reference  or
provided  in this  prospectus  or any  supplement  or term  sheet.  We have  not
authorized anyone to provide you with different  information.  We are not making
an offer of these securities in any state where the offer is not permitted.  You
should not assume that the  information in this  prospectus or any supplement or
term sheet is  accurate as of any date other than the date on the front of these
documents.

    We maintain a website on the World Wide Web at http://www.calwater.com where
certain additional information about us may be found. We undertake no obligation
to update the information  found on our website.  The information on the website
is not a part of this prospectus of any prospectus  supplement or term sheet, or
of the registration statement, but is referenced and maintained as a convenience
to investors.


                                       25



                      [CALIFORNIA WATER SERVICE GROUP LOGO]


                                       26



                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

              ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION

    Expenses  in  connection  with the  offering of the entire  $120,000,000  of
    securities will be borne by the registrant and are estimated as follows:

SEC registration fee.........................     $       9,708
Rating agency fees...........................     $      60,000
Trustee's fees and expenses..................     $      40,000
Accountant's fees and expenses...............     $     650,000
Legal fees and expenses......................     $     940,000
Printing costs...............................     $      90,000
Blue Sky fees and expenses...................     $       5,000
Miscellaneous expenses.......................     $     205,292
                                                  -------------
 Total.......................................     $   2,000,000
                                                  =============

ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS


The company 's Certificate of  Incorporation  provides that the liability of our
directors,  both to the company and to its  stockholders,  for monetary damages,
including  liability  for breach of fiduciary  duty,  shall be eliminated to the
fullest extent  permissible  under Delaware law. The  Certificate  also provides
that  the  company  shall  indemnify  any  person  who is or was a  party  or is
threatened to be made a party to any  proceeding by reason of the fact that that
person is or was an agent of the  company,  to the fullest  extent  permitted by
Section 145 of the Delaware General  Corporation Law. The company also maintains
officers and director's liability insurance.


ITEM 16. EXHIBITS

See Exhibit Index immediately following the signature page hereof.

ITEM 17. UNDERTAKINGS

    (a) We hereby undertake:

         (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this registration statement:

                  (i) To include any prospectus  required by Section 10(a)(3) of
the Securities Act;

                  (ii) To reflect in the  prospectus any facts or events arising
after the  effective  date of the  registration  statement  (or the most  recent
post-effective  amendment  thereof)  which,  individually  or in the  aggregate,
represent a fundamental  change in the information set forth in the registration
statement.  Notwithstanding the foregoing, any increase or decrease in volume of
securities  offered (if the total dollar value of  securities  offered would not
exceed that which was  registered) and any deviation from the low or high end of
the estimated  maximum offering range may be reflected in the form of prospectus
filed with the  Commission  pursuant  to Rule 424(b) if, in the  aggregate,  the
changes in volume and price  represent  no more than a 20 percent  change in the
maximum  aggregate  offering price set forth in the "Calculation of Registration
Fee" table in the effective registration statement; and

                  (iii) To include any material  information with respect to the
plan of distribution not previously  disclosed in the registration  statement or
any material change to such information in the registration statement;

provided,  however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the
information  required  to be  included in a  post-effective  amendment  by those
paragraphs  is  contained  in periodic  reports  filed with or  furnished to the
Commission  by us pursuant to Section 13 or 15(d) of the  Exchange  Act that are
incorporated by reference in the registration statement.

                                       27


         (2) That,  for the  purpose  of  determining  any  liability  under the
Securities Act, each such  post-effective  amendment shall be deemed to be a new
registration  statement  relating to the  securities  offered  therein,  and the
offering of such  securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3) To remove from registration by means of a post-effective  amendment
any of the securities being registered which remain unsold at the termination of
the offering.

    (b) We hereby  undertake  that,  for purposes of  determining  any liability
under the Securities  Act, each filing of our annual report  pursuant to Section
13(a) or Section 15(d) of the Exchange Act that is  incorporated by reference in
this registration  statement shall be deemed to be a new registration  statement
relating to the securities  offered herein,  and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

    (c) We  hereby  undertake  to  provide  to the  underwriter  at the  closing
specified in the underwriting agreements, certificates in such denominations and
registered  in such  names as  required  by the  underwriter  to  permit  prompt
delivery to each purchaser.

    (d) Insofar as indemnification  for liabilities arising under the Securities
Act may be permitted to our directors, officers and controlling persons pursuant
to the  provisions  referred to in Item 15 hereof,  or  otherwise,  we have been
advised that in the opinion of the Commission  such  indemnification  is against
public  policy  as  expressed  in  the   Securities   Act  and  is,   therefore,
unenforceable.  In the  event  that a claim  for  indemnification  against  such
liabilities  (other  than the  payment by us of  expenses  incurred or paid by a
director,  officer or  controlling  person of the  registrant in the  successful
defense of any action, suit or proceeding) is asserted by such director, officer
or controlling  person in connection with the securities  being  registered,  we
will,  unless in the  opinion of our  counsel  the  matter  has been  settled by
controlling  precedent,  submit  to a  court  of  appropriate  jurisdiction  the
question  whether  such  indemnification  by  us is  against  public  policy  as
expressed in the Securities  Act and will be governed by the final  adjudication
of such issue.

    (e) We hereby undertake that:

         (1) For purposes of determining any liability under the Securities Act,
the  information  omitted  from  the  form of  prospectus  filed as part of this
registration  statement  in reliance  upon Rule 430A and  contained in a form of
prospectus  filed by us pursuant to Rule  424(b)(1)  or (4) or 497(h)  under the
Securities Act shall be deemed to be part of this  registration  statement as of
the time it was declared effective.

         (2) For the purpose of determining  any liability  under the Securities
Act, each  post-effective  amendment that contains a form of prospectus shall be
deemed to be a new  registration  statement  relating to the securities  offered
therein,  and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

    (f) The undersigned  registrant hereby undertakes to file an application for
the  purpose  of  determining  the  eligibility  of the  trustee  to  act  under
Subsection (a) of Section 310 of the Trust  Indenture Act in accordance with the
rules and regulations  prescribed by the Commission  under Section  305(b)(2) of
the Act.


                                       28



                                   SIGNATURES


Pursuant to the  requirements  of the  Securities  Act of 1933, as amended,  the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this amendment to
registration statement to be signed on its behalf by the undersigned,  thereunto
duly authorized, in the City of San Jose, State of California, on June 6, 2003.


                                CALIFORNIA WATER SERVICE GROUP

                                By: /s/ Peter C. Nelson*
                                    --------------------------------------------
                                     Peter C. Nelson
                                     President and Chief Executive Officer
                                     (Principal Executive Officer)



Pursuant  to  the   requirements  of  the  Securities  Act,  this  amendment  to
registration  statement  has  been  signed  by  the  following  persons  in  the
capacities and on the dates indicated.



          Signature                                      Title                                      Date
          ---------                                      -----                                      ----

                                                                                             
/s/ Peter C. Nelson*                        President and Chief Executive                          June 6, 2003
- ------------------------------------        Officer (Principal Executive
Peter C. Nelson                             Officer) and Director


/s/ Richard D. Nye                          Vice President, Chief Financial                        June 6, 2003
- ------------------------------------        Officer and Treasurer (Principal
Richard D. Nye                              Financial Officer)


/s/ Robert W. Foy                           Director,                                              June 6, 2003
- ------------------------------------        Chairman of the Board of Directors
Robert W. Foy

/s/ Calvin L. Breed                         Controller                                             June 6, 2003
- ------------------------------------        (Principal Accounting Officer)
Calvin L. Breed

/s/ Douglas M. Brown*                       Director                                               June 6, 2003
- ------------------------------------
Douglas M. Brown

/s/ Edward D. Harris, Jr., M.D.*            Director                                               June 6, 2003
- ------------------------------------
Edward D. Harris, Jr., M.D.

/s/ Richard P. Magnuson*                    Director                                               June 6, 2003
- ------------------------------------
Richard P. Magnuson

/s/ Linda R. Meier*                         Director                                               June 6, 2003
- ------------------------------------
Linda R. Meier

/s/ George A. Vera*                         Director                                               June 6, 2003
- ------------------------------------
George A. Vera

*By /s/ Peter C. Nelson                     Individually and as Attorney-in-Fact                   June 6, 2003
   ---------------------------------
      Peter C. Nelson
      Attorney in Fact




                                       29



                                  EXHIBIT INDEX

1        Underwriting  Agreement  between  California  Water  Service  Group and
         Edward D. Jones & Co., L.P.*

3.1      Certificate  of   Incorporation   of  California  Water  Service  Group
         (incorporated  by  reference  to  Exhibit A of the  Registrant's  Proxy
         Statement dated March 18, 1999**)

3.2      Restated  By-laws  of  California  Water  Service  Group as  amended on
         January 26, 2000  (incorporated by reference to Exhibit 3-2 to Form 8-K
         dated January 26, 2000**)


4.       Form of Indenture for Debt Securities  between California Water Service
         Group and U.S. Bank National Association as Trustee (previously filed)

5.1      Opinion of Bingham McCutchen LLP ***

12.1     Computation of Ratios of Earnings to Fixed Charges for each of the five
         years ended  December  31, 2002 and for the  twelve-month  period ended
         March 31, 2003***

12.2     Computation of Ratios of Earnings to Fixed Charges and Preferred  Stock
         Dividends  for each of the five years ended  December  31, 2002 and for
         the twelve-month period ended March 31, 2003***

23.1     Consent of Bingham  McCutchen LLP (included in their opinion in Exhibit
         5.1)

23.2     Consent of KPMG LLP as independent auditors***

24       Power of attorney of certain officers and directors of California Water
         Service Group (included in signature page of the original  registration
         statement)

25       Statement of Eligibility of Trustee on Form T-1 (previously filed)

- -----------
*      To be filed as an exhibit to a Current Report on Form 8-K.
**     File No. 1-13883.

***    Filed herewith.




                                       30