AMENDMENT TO FORM 10-K ANNUAL REPORT

                       SECURITIES AND EXCHANGE COMMISSION

                              Washington, DC 20549

                                 AMENDMENT NO. 1

           [ X ] ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                  For the fiscal year ended: December 31, 2000

                                       OR

          [ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                        For the transition period ended:
                           _________________________

                         Commission File Number: 1-7211

                              IONICS, INCORPORATED
             (Exact name of registrant as specified in its charter)

          MASSACHUSETTS                                 04-2068530
(State or other jurisdiction               (IRS Employer Identification Number)
 of incorporation or organization)

65 Grove Street, Watertown, Massachusetts               02472
(Address of principal executive offices)              (Zip Code)

       Registrant's telephone number, including area code: (617) 926-2500


Securities registered pursuant to Section 12(b) of the Act:

                 Title of each class: Common Stock, $1 par value

       Name of each exchange on which registered: New York Stock Exchange

Securities registered pursuant to Section 12(g) of the Act:

                                      None
                                (Title of Class)



The  undersigned   registrant  hereby  amends  the  following  items,  financial
statements, exhibits or other portions of its Annual Report on Form 10-K for the
fiscal year ended December 31, 2000 as set forth in the pages attached hereto:

1. Item 14(a) 3. of Part IV of said  report on Form 10-K is amended to list Form
11-K, Annual Report of the Ionics Section 401(k) Stock Savings Plan for the year
ended  December  31, 2000 as Exhibit  13(b)  thereto.  The Annual  Report of the
Ionics  Section  401(k)  Stock  Savings  Plan on Form  11-K for the  year  ended
December  31,  2000  is  hereby  filed  pursuant  to  Rule  15d-21  and  General
Instruction F to Form 10-K as an Exhibit to said Annual Report on Form 10-K.

Pursuant  to the  requirements  of the  Securities  Exchange  Act of  1934,  the
registrant  has duly  caused  this  amendment  to be signed on its behalf by the
undersigned, thereunto duly authorized.

                                         IONICS, INCORPORATED
                                         (Registrant)



Date:  June 26, 2001                      By  /s/Stephen Korn
                                              -----------------------
                                              Stephen Korn
                                              Vice President and
                                              General Counsel





                                     PART IV

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K
         ---------------------------------------------------------------

(a)  1.   Financial Statements

          See Index to  Financial  Statements  and  Financial  Schedules on page
          IV-7.  The  Financial  Statement  Schedules  are filed as part of this
          Annual Report on Form 10-K.

     2.   Financial Statement Schedules

          See Index to Financial Statements and Financial Statement Schedules on
          page IV-7.

     3.   Exhibits


          Exhibit No.  A.  Description
          -----------  --  -----------

          3.0          Articles of Organization and By-Laws

                       3.1     Restated Articles of Organization            *
                               filed April 16, 1986 (filed as
                               Exhibit 3.1 to the Company's Annual
                               Report on Form 10-K for the year
                               ended December 31, 1997).

                       3.1(a)  Amendment to Restated Articles of            *
                               Organization filed June 19, 1987
                               (filed as Exhibit 3.1(a) to the
                               Company's Annual Report on Form
                               10-K for the year ended December
                               31, 1997).

                       3.1(b)  Amendment to Restated Articles of            *
                               Organization filed May 13, 1988
                               (filed as Exhibit 3.1(b) to
                               Registration Statement No. 33-38290
                               on Form S-2 effective January 24,
                               1991).

                       3.1(c)  Amendment to Restated Articles of            *
                               Organization filed May 8, 1992
                               (filed as Exhibit 3.1 to the
                               Company's Quarterly Report on
                               Form 10-Q for the quarterly period
                               ending June 30, 1996.

                       3.1(d)  Amendment to Restated Articles of            *
                               Organization filed May 8, 1998
                               (filed as Exhibit 3.1 to the
                               Company's Quarterly Report on Form
                               10-Q for the quarterly period ending
                               March 31, 1998).

                       3.2     By-Laws, as amended through May 2,           *
                               2000 (filed as Exhibit 3.2 to the
                               Company's Quarterly Report on Form
                               10-Q for the quarterly period ended
                               March 31, 2000).

          4.0         Instruments   defining  the  rights  of  security holders,
                      including indentures


                      4.1      Renewed Rights Agreement, dated as           *
                               of August 19, 1997 between Registrant
                               and BankBoston N.A. (filed as Exhibit
                               1 to the Company's Current Report on
                               Form 8-K dated August 27, 1997).

                      4.2      Form of Common Stock Certificate             *
                               (filed as Exhibit 4.2 to the
                               Company's Annual Report on Form 10-K for
                               the year ended December 31, 1997)


          10.0        Material Contracts

                      10.1     1979 Stock Option Plan, as amended           *
                               through February 22, 1996 (filed as
                               Exhibit 10.1 to the Company's Annual
                               Report on Form 10-K for the year
                               ended December 31, 1995).

                      10.2     1986 Stock Option Plan for Non-Employee      *
                               Directors, as amended through February 19,
                               1997 (filed as Exhibit 10.2 to the
                               Company's Annual Report on Form 10-K
                               for the year ended December 31, 1996).

                      10.3     Second Amended and Restated Credit           *
                               Agreement dated as of July 28, 2000,
                               among the Company, Fleet National
                               Bank and Fleet National Bank as agent
                               (filed as Exhibit 10.1 to the Company's
                               Quarterly Report on Form 10-Q for the
                               quarterly period ended June 30, 2000.)

                      10.3(1)  Amended Agreement No. 1 to Second Amended
                               and Restated Credit Agreement among the
                               Company, Fleet National Bank and Fleet
                               National Bank as Agent dated March 1, 2001.

                      10.3(2)  Security Agreement dated as of
                               March 1, 2001 by and among the
                               Company, certain of its domestic
                               subsidiaries, and Fleet National Bank
                               as agent.

                      10.3(3)  Escrow Agreement dated as of
                               March 1, 2001 by and among the
                               Company, Hutchins, Wheeler & Dittmar,
                               and Fleet National Bank as agent.

                      10.3(4)  Seventh Amended and Restated Revolving
                               Credit Note dated March 1, 2001.

                      10.4     Operating Agreement dated as                 *
                               of September 27, 1989 between the
                               Company and Aqua Cool Enterprises,
                               Inc. (filed as Exhibit 10.4 to the
                               Company's Annual Report on
                               Form 10-K for the year ended December
                               31, 1997).

                      10.5     Term Lease Master Agreement                  *
                               dated as of September 27, 1989
                               between the Company and
                               Aqua Cool Enterprises, Inc. (filed as
                               Exhibit 10.5 to the Company's Annual
                               Report on Form 10-K for the year ended
                               December 31, 1997).


                      10.6     Option Agreement dated as of September       *
                               27, 1989 among the Company, Aqua Cool
                               Enterprises, Inc. and the other parties
                               named therein (filed as Exhibit to the
                               Company's registration statement on Form
                               S-2, No. 33-38290, effective January 24,
                               1991).

                      10.7     1994 Restricted Stock Plan (filed as         *
                               Exhibit 10.12 to the Company's Annual
                               Report on Form 10-K dated March 30, 1995).

                      10.8     1997 Stock Incentive Plan (filed as          *
                               Exhibit 10.12 to the Company's Annual
                               Report on Form 10-K dated December 31,
                               1996).

                      10.9     Ionics, Incorporated Supplemental            *
                               Executive Retirement Plan effective
                               as of January 1, 1996 (filed as Exhibit
                               10.9 to the Company's Annual Report
                               on Form 10-K dated December 31, 1997).

                      10.10    Form of Employee Retention Agreement         *
                               dated February 24, 1998 between the
                               Company and certain officers of the
                               Company and its subsidiaries (filed
                               as Exhibit 10.10 to the Company's
                               Annual Report on Form 10-K dated
                               December 31, 1997).

                      10.11    1998 Non-Employee Directors Fee Plan         *
                               (filed as Exhibit 10.1 to the Company's
                               Quarterly Report on Form 10-Q for the
                               quarterly period ending September 30, 1998).

                      10.12    Shareholders' Agreement dated as of          *
                               May 12, 2000, by and among the Company,
                               Hafeez Karamath Engineering Services
                               Limited, and Desalination Company of
                               Trinidad and Tobago Ltd., as amended on June
                               16, 2000 (filed as Exhibit 10.2 to the
                               Company's Quarterly Report on Form
                               10-Q for the quarterly period ended
                               June 30, 2000.)

                      10.13    Loan Agreement dated as of October 25,
                               2000 between the Company and Hafeez
                               Karamath Engineering Services Limited.

         13.0(a)      Annual Report to Stockholders for
                      the year ended December 31, 2000 (furnished for
                      the information of the Commission and not to be
                      deemed "filed" as part of this Report except to
                      the extent that portions thereof are expressly
                      incorporated herein by reference).

         13.0(b)      Annual Report of the Ionics Section 401(k)
                      Stock Savings Plan on Form 11-K for the year
                      ended December 31, 2000.

         21.0         Subsidiaries of the Registrant.

         23.0         Consents


                      23.1     Consent of PricewaterhouseCoopers LLP to
                               incorporation by reference of that
                               firm's report dated March 19, 2001,
                               which is contained in the Registrant's
                               Annual Report to Stockholders for the
                               year ended December 31, 2000, and is
                               included on page 6 of Exhibit 13 to
                               this Form 10-K.

         24.0        Power of Attorney.
         --------------------------
         *incorporated herein by reference

(b)      Reports on Form 8-K

         No reports on Form 8-K were  filed by the  Registrant  during the last
         quarter of fiscal 2000.






                 Exhibit No. 13(b) to Annual Report on Form 10-K
          of Ionics, Incorporated for the year ended December 31, 2000



                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 11-K




   [X] Annual report pursuant to Section 15(d) of the Securities Exchange Act
                                     of 1934

                   For the fiscal year ended December 31, 2000

                                       OR

 [ ] Transition report pursuant to Section 15(d) of the Securities Exchange Act
                                     of 1934

             For the transition period from __________ to __________

                         Commission File Number: 1-7211


A.   Full title of the plan and the address of the plan, if different  from that
     of the issuer named below: Ionics Section 401(k) Stock Savings Plan

B.   Name of issuer of the securities  held pursuant to the plan and the address
     of its principal  executive  office:
                              IONICS, INCORPORATED
                                65 Grove Street
                            Watertown, MA 02472-2882




                    IONICS SECTION 401(k) STOCK SAVINGS PLAN

            INDEX OF FINANCIAL STATEMENTS AND SUPPLEMENTAL SCHEDULES

                 FOR THE YEARS ENDED DECEMBER 31, 2000 AND 1999




                                                                         Page
                                                                         ----

Independent Auditor's Report                                               3

Financial Statements:

     Statements of Net Assets Available for Benefits
     at December 31, 2000 and 1999                                         4

     Statements of Changes in Net Assets Available for
     Benefits for the year ended December 31, 2000                         5

Notes to Financial Statements                                              6

Supplemental Schedules:

     Schedule of Assets Held for Investment Purposes at
     December 31, 2000                                                     9




                          INDEPENDENT AUDITOR'S REPORT


Administrators
Ionics Section 401(k) Stock Savings Plan
Watertown, Massachusetts

We have audited the accompanying statements of net assets available for benefits
of the Ionics  Section  401(k) Stock  Savings Plan (the Plan) as of December 31,
2000 and 1999, and the related  statement of changes in net assets available for
benefits for the year ended December 31, 2000.  These  financial  statements and
the schedule referred to below are the responsibility of the plan administrator.
Our  responsibility  is to express an opinion on these financial  statements and
schedules based on our audits.

We  conducted  our  audits  in  accordance  with  generally   accepted  auditing
standards. Those standards require that we plan and perform the audits to obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements.  An audit also includes
assessing the  accounting  principles  used and  significant  estimates  made by
management,  as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.

In our opinion,  the financial  statements  referred to above present fairly, in
all material  respects,  the net assets available for benefits of the Plan as of
December  31,  2000 and 1999 and the  changes  in its net assets  available  for
benefits for the year ended  December 31, 2000,  in  conformity  with  generally
accepted accounting principles.

Our  audits  were  made for the  purpose  of  forming  an  opinion  on the basic
financial statements taken as a whole. The supplemental  schedule of assets held
for  investment  purposes  is  presented  for  purposes  of  complying  with the
Department of Labor Rules and Regulations for Reporting and Disclosure under the
Employee  Retirement  Income Security Act of 1974 and are not a required part of
the basic financial statements. Such schedule has been subjected to the auditing
procedures  applied in the audit of the basic  financial  statements and, in our
opinion,  is fairly stated, in all material  respects,  in relation to the basic
financial statements taken as a whole.





                                        BELANGER & COMPANY, P.C.
                                        CERTIFIED PUBLIC ACCOUNTANTS

Chelmsford, Massachusetts
June 8, 2001




                    IONICS SECTION 401(k) STOCK SAVINGS PLAN
                 STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS



                                                     December 31,
                                         -------------------------------------
                                                2000                1999
                                         -----------------    ----------------

Assets:
     Investments (see Note C)               $ 25,348,894         $ 23,838,501
                                         -----------------    ----------------

Receivables:
     Employer contribution                        54,346               58,744
     Participant contributions                   264,942              245,022
                                         -----------------    ----------------

     Total receivables                           319,288              303,766
                                         -----------------    ----------------

     Total assets                             25,668,182           24,142,267

Liabilities                                            0                    0
                                         -----------------    ----------------

Net assets available for benefits           $ 25,668,182         $ 24,142,267
                                         =================    ================


See accompanying Notes to the financial statements.



                    IONICS SECTION 401(k) STOCK SAVINGS PLAN
            STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS




                                                                Year Ended
                                                             December 31, 2000
                                                             -----------------
Additions:
  Additions to net assets attributed to:
   Investment income:
     Net depreciation in fair value of investments (see Note C)  $ (440,865)
     Interest                                                       140,897
     Dividends                                                      174,522
                                                               ----------------
                                                                   (125,446)
                                                               ----------------

   Contributions:
     Participant                                                  3,172,834
     Employer                                                       689,653
                                                               ----------------
                                                                  3,862,487
                                                               ----------------

     Total additions                                              3,737,041

Deductions:
  Withdrawals by and distributions to participants                2,211,126
                                                               ----------------

     Net increase                                                 1,525,915

Net assets available for benefits:
  Beginning of year                                              24,142,267
                                                              -----------------

  End of year                                                  $ 25,668,182
                                                              =================


See accompanying Notes to the financial statements.




NOTES TO FINANCIAL STATEMENTS


A.   Description of Plan

     The  following  description  of  the  Ionics,   Incorporated  and  domestic
     subsidiaries   ("Company")   401(k)  Plan  (Plan)   provides  only  general
     information.  Participants  should refer to the Plan  agreement  for a more
     complete description of the Plan's provisions.

1.   General.  The Plan is a defined  contribution  plan  covering all permanent
     employees  of the  Company  working  at least  20  hours  per week who have
     completed  one  year of  service  (effective  March 1,  2000,  the Plan was
     amended to permit new employees to become eligible to participate effective
     as of the first  day of the month  coincident  with or next  following  the
     employee's date of hire).

2.   Contributions.  Each year,  participants may contribute up to 12 percent of
     pretax annual compensation,  as defined in the Plan.  Participants may also
     contribute amounts representing  distributions from other qualified defined
     benefit or defined  contribution plans.  Participants direct the investment
     of their contributions into various investment options offered by the Plan.
     The  Plan  currently  offers  Company  stock  and  seven  mutual  funds  as
     investment  options for  participants.  The Company  contributes 50% of the
     first 6 percent of base compensation that a participant  contributes to the
     Company stock portion of the Plan.  The matching  Company  contribution  is
     invested directly in Ionics,  Incorporated common stock.  Contributions are
     subject to certain limitations.

3.   Participant  Accounts.  Each  participant's  account is  credited  with the
     participant's   contribution   and   allocations   of  (a)  the   Company's
     contribution  and  (b)  Plan  earnings.  Allocations  are  based  on  total
     investment  earnings  and  average  participant   investment  balances,  as
     defined. The benefit to which a participant is entitled is the benefit that
     can be provided from the participant's vested account.

4.   Vesting.  Participants are vested  immediately in their  contributions plus
     actual earnings thereon.  Vesting in the Company's  contribution portion of
     their accounts is based on years of continuous service ranging from 33 1/3%
     after two years to 100% after four years.

5.   Participant  Loans.  Participants  may borrow  from  their fund  accounts a
     minimum  of  $1,000,  up to a maximum  of  $50,000  or 50  percent of their
     account balance, whichever is less. The loans are secured by the balance in
     the participant's  account and bear interest at rates that are commensurate
     with local prevailing rates as determined by the Plan administrator.

6.   Payment of Benefits. On termination of service due to death, disability, or
     retirement,  a participant  may elect to receive  either a lump-sum  amount
     equal  to the  value of the  participant's  vested  interest  in his or her
     account, or annual installments over the life expectancy of the Participant
     (or  the  joint  life   expectancy  of  the   Participant   and  spouse  or
     beneficiary).

7.   Plan Expenses. The Plan provides that the Company shall pay all expenses of
     the Plan and its administration.

B.   Summary of Accounting Policies

     Use of Estimates

     The  preparation  of financial  statements  in  conformity  with  generally
     accepted  accounting  principles  requires management to make estimates and
     assumptions  that affect the reported amounts of assets and liabilities and
     changes  therein,  and  disclosure  of contingent  assets and  liabilities.
     Actual results could differ from those estimates.





     Investment Valuation and Income Recognition

     Investment  of the Plan in Ionics,  Incorporated  Common Stock is stated at
     the last sales price on December 31, 2000 as reported on the New York Stock
     Exchange.  Shares of  mutual  funds  are  valued at the Net Asset  Value of
     shares held by the Plan at year-end.

     Purchases  and sales of  securities  are  recorded on a  trade-date  basis.
     Dividends are recorded on the ex-dividend date.

C.   Investments

     The following presents  investments that represent 5 percent or more of the
     Plan's net assets.

                                                           December 31,
                                                    --------------------------
                                                         2000          1999
                                                    ------------    ----------

Ionics, Incorporated common stock,
436,598 and 393,964 shares, respectively           $ 12,388,468    $ 11,079,956

Puritan Fund, 114,594 and 116,782
shares, respectively                                  2,157,798       2,222,346

Contrafund Fund, 99,513 and 89,090
shares, respectively                                  4,893,052       5,347,159

Janus Worldwide Fund, 26,252 and 13,831
shares, respectively                                  1,492,678       1,057,112


     During  2000,  the  Plan's  investments  (including  gains  and  losses  on
     investments  bought and sold, as well as held during the year)  depreciated
     in value by $1,409,296 as follows:

Mutual funds                                       $ (1,679,628)
Ionics, Incorporated common stock                       270,332
                                                  ---------------
                                                   $ (1,409,296)
                                                  ===============

D.   Plan Termination

     Although  it has not  expressed  any intent to do so, the  Company  has the
     right under the Plan to discontinue  its  contributions  at any time and to
     terminate the Plan subject to the provisions of ERISA. In the event of Plan
     termination, participants will become 100 percent vested in their accounts.

E.   Reconciliation of Financial Statements to Form 5500

     The following is a reconciliation  of net assets available for benefits per
     the financial statements at December 31, 2000 and 1999 to Form 5500:

                                                    2000              1999
                                              --------------   ---------------
Net assets available for benefits per the
financial statements                           $ 25,668,182      $ 24,142,267

Amounts allocated to withdrawing
participants                                       (301,050)          (88,211)
                                              --------------   ---------------

Net assets available for benefits per the
Form 5500                                      $ 25,367,132      $ 24,054,056
                                              ==============   ===============


     The following is a reconciliation  of benefits paid to participants per the
     financial statements for the year ended December 31, 2000 to Form 5500:

Distributions to participants per the
financial statements:                           $ 2,211,126

Add:  Amounts allocated to withdrawing
participants at December 31, 2000                   301,050

Less: Amounts allocated to withdrawing
participants at December 31, 1999                   (88,211)
                                              --------------

Benefits paid to participants per Form 5500     $ 2,423,965
                                              ==============

     Amounts allocated to withdrawing participants are recorded on the Form 5500
     for benefit  claims that have been processed and approved for payment prior
     to December 31st but not yet paid as of that date.

F.   Tax Status

     The Internal  Revenue  Service has determined and informed the Company by a
     letter  dated  September  12,  1995,  that the Plan and  related  trust are
     designed in accordance  with  applicable  sections of the Internal  Revenue
     Code  (IRC).  Although  the Plan  has  been  amended  since  receiving  the
     determination  letter,  it is  believed  that the Plan is  designed  and is
     currently being operated in compliance with the applicable  requirements of
     the IRC.




Attachment to Form 5500
Schedule H, Line 4i
EIN: 04-2068530
PN: 003
                    IONICS SECTION 401(k) STOCK SAVINGS PLAN
                 SCHEDULE OF ASSETS HELD FOR INVESTMENT PURPOSES
                                DECEMBER 31, 2001



                                 Face Amount        Current
Description of Investment       Shares or Rate        Cost             Value
- --------------------------      --------------   --------------   --------------

Ionics, Incorporated
Common Stock                         436,598     $ 12,086,923     $ 12,388,468

Fidelity Investments:
Puritan Fund                         114,594        2,057,901        2,157,798
Contrafund                            99,513        4,829,269        4,893,052

MainStay Institutional:
Indexed Bond                          45,299          488,460          471,110
Asset Manager Fund                    95,541        1,486,721        1,269,745
Indexed Equity Fund                   16,546          563,824          527,651
Money Market                                          146,189          146,189

Janus Worldwide Fund                  26,252        1,627,727        1,492,678

BT Pyramid GIC Fund                                 1,197,003        1,197,003

Participant Loans
(Rate of interest 7.43% to 10.50%)                          0          805,200
                                                --------------   --------------

Total funds invested                             $ 24,484,017     $ 25,348,894
                                                ==============   ==============

The accompanying Notes are an integral part of these financial schedules.




                                   SIGNATURES




Ionics Section 401(k) Stock Savings Plan.  Pursuant to the  requirements  of the
Securities  Exchange Act of 1934,  the trustee (or other persons who  administer
the employee  benefit  plan) has duly caused this annual  report to be signed on
its behalf by the undersigned hereunto duly authorized.

                                  IONICS SECTION 401(k) STOCK
                                  SAVINGS PLAN


Date:  June 26, 2001              By: /s/ Daniel M. Kuzmak
                                      -----------------------------
                                      Daniel M. Kuzmak, Member
                                      Plan Administrative Committee




                                    EXHIBIT 1



                       CONSENT OF INDEPENDENT ACCOUNTANTS



We consent to the  incorporation by reference in the  registration  statement of
the Ionics  Section  401(k)  Stock  Savings Plan on Form S-8  (Registration  No.
33-2092)  of our  report  dated  June 8,  2001 on our  audits  of the  financial
statements  of the Ionics  Section  401(k) Stock Savings Plan as of December 31,
2000 and 1999,  which  report is included in this Annual  Report on Form 11-K of
the Plan which is being filed as Exhibit 13(b) to the Annual Report on Form 10-K
of Ionics, Incorporated for the year ended December 31, 2000.





                                              BELANGER & COMPANY, P.C.
                                              CERTIFIED PUBLIC ACCOUNTANTS

Chelmsford, Massachusetts
June 19, 2001