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                         NOTICE OF GUARANTEED DELIVERY
    
                   11 1/4% SENIOR SUBORDINATED NOTES DUE 2008
                                       OF
 
                                AQUA-CHEM, INC.
   
                PURSUANT TO THE PROSPECTUS DATED JANUARY 5, 1999
    
 
   
     This form must be used by a holder of 11 1/4% Senior Subordinated Notes Due
2008 (the "Notes") of Aqua-Chem, Inc., a Delaware corporation (the "Company"),
who wishes to tender Notes to the Exchange Agent pursuant to the guaranteed
delivery procedures described under the caption "The Exchange Offer -- How to
Tender" in the Company's Prospectus dated January 5, 1999 (the "Prospectus") and
in Instruction 2 to the related Letter of Transmittal. Any holder who wishes to
tender Notes pursuant to such guaranteed delivery procedures must ensure that
the Exchange Agent receives this Notice of Guaranteed Delivery prior to the
Expiration Date of the Exchange Offer. Capitalized terms used but not defined
herein have the meanings ascribed to them in the Prospectus or the Letter of
Transmittal.
    
 
                 THE EXCHANGE OFFER AND WITHDRAWAL RIGHTS WILL
          EXPIRE AT 5:00 P.M., NEW YORK CITY TIME, ON FEBRUARY 5, 1999
                    UNLESS EXTENDED (THE "EXPIRATION DATE").
 
                    UNITED STATES TRUST COMPANY OF NEW YORK
                             (THE "EXCHANGE AGENT")
 


          By Mail:             Facsimile Transmission Number:    By Hand up to 4:30 p.m.:
          --------             ------------------------------    ------------------------
                                                         
 United States Trust Company          (212) 780-0592            United States Trust Company
         of New York            (For Eligible Institutions              of New York
        P.O. Box 844                       Only)                       111 Broadway
       Cooper Station                                                   Lower Level
     New York, New York            Confirm by Telephone:         New York, New York 10006
         10276-0844                                                Attn: Corporate Trust
    Attn: Corporate Trust              (800)548-6565                     Services
          Services
(Registered or Certified Mail
        Recommended)

 


                                 By Overnight Courier and
                                by Hand after 4:30 p.m. on
                                 the Expiration Date Only:
                                --------------------------
                                                        
                                United States Trust Company
                                            of
                                         New York
                                       770 Broadway
                                        13th Floor
                                 New York, New York 10003
                                   Attn: Corporate Trust
                                         Services

 
     DELIVERY OF THIS INSTRUMENT TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE OR
TRANSMISSION OF INSTRUCTIONS VIA A FACSIMILE NUMBER OTHER THAN THE ONE LISTED
ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
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     This form is not to be used to guarantee signatures. If a signature on a
Letter of Transmittal is required to be guaranteed by an "Eligible Institution"
under the instructions thereto, such signature guarantee must appear in the
applicable space provided in the signature box on the Letter of Transmittal.
 
Ladies and Gentlemen:
 
     The undersigned hereby tenders to the Company, upon the terms and subject
to the conditions set forth in the Prospectus and the related Letter of
Transmittal, receipt of which is hereby acknowledged, the principal amount of
Notes set forth below pursuant to the guaranteed delivery procedures set forth
in the Prospectus and in Instruction 2 of the Letter of Transmittal.
 
     All authority conferred or agreed to be conferred by this Notice of
Guaranteed Delivery shall not be affected by, and shall survive, the death or
incapacity of the undersigned, and every obligation of the undersigned under
this Notice of Guaranteed Delivery shall be binding upon the heirs, executors,
administrators, trustees in bankruptcy, personal and legal representatives,
successors and assigns of the undersigned.
 
     The undersigned hereby tenders the Notes listed below:
 


- ---------------------------------------------------------------------------------------------------
CERTIFICATE NUMBER(S) (IF KNOWN) OF
   NOTES OR AGGREGATE PRINCIPAL          ACCOUNT NUMBER AT THE            AGGREGATE PRINCIPAL
        AMOUNT REPRESENTED                BOOK-ENTRY FACILITY               AMOUNT TENDERED
- ---------------------------------------------------------------------------------------------------
                                                              
- ---------------------------------------------------------------------------------------------------
- ---------------------------------------------------------------------------------------------------
- ---------------------------------------------------------------------------------------------------
- ---------------------------------------------------------------------------------------------------
- ---------------------------------------------------------------------------------------------------

 
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                            PLEASE SIGN AND COMPLETE
- --------------------------------------------------------------------------------
 
 Signature(s) of Registered Holder(s) or
 Authorized Signatory:
 -------------------------------
 -------------------------------------------------------
 Name(s) of Registered Holder(s):
 -----------------
 -------------------------------------------------------
 Principal Amount of Notes Tendered and as to
 which Consents are given:
 --------------------------
 Certificate No(s). of Notes
 (if available):
 ---------------------------------------
Date:
- ------------------------------------------------
Address:
- ---------------------------------------------
 
         ------------------------------------------------------
Area Code and Telephone No.:
- --------------------
If Notes will be delivered by book-entry
transfer to DTC, check the box: [ ]
DTC Account
No.:
- -------------------------------------------------
 
      This Notice of Guaranteed Delivery must be signed by the holder(s)
 exactly as their name(s) appear on certificates for the Notes or on a security
 position listing as the owner of Notes, or by person(s) authorized to become
 holder(s) by endorsements and documents transmitted with this Notice of
 Guaranteed Delivery. If signature is by a trustee, executor, administrator,
 guardian, attorney-in-fact, officer or other person acting in a fiduciary or
 representative capacity, such person must provide the following information.
 
 Please print name(s) and address(es).
 
 Name(s):
 ------------------------------------------------------------------------------
 
          ---------------------------------------------------------------------
 
 Capacity:
 ------------------------------------------------------------------------------
 
         ----------------------------------------------------------------------
 
 Address(es):
 ------------------------------------------------------------------------------
 
            -------------------------------------------------------------------
 
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                                   GUARANTEE
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
     The undersigned, a firm which is a member of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.,
or is a commercial bank or trust company having an office or correspondent in
the United States, or is otherwise an "eligible guarantor institution" within
the meaning of Rule 17Ad-15 under the Securities Exchange Act of 1934, as
amended, guarantees deposit with the Exchange Agent of the Letter of Transmittal
(or facsimile thereof), together with the Notes tendered hereby in proper form
for transfer (or confirmation of the book-entry transfer of such Notes into the
Exchange Agent's account at the Book-Entry Transfer Facility described in the
Prospectus under the caption "The Exchange Offer -- How to Tender" and in the
Letter of Transmittal) and any other required documents, all by 5:00 p.m., New
York City time, on the third New York Stock Exchange trading day following the
Expiration Date.
 
                      PLEASE PRINT NAMES(S) AND ADDRESS(S)
 
Name of firm:
- --------------------------------------------------------------------------------
 
Authorized Signature:
- --------------------------------------------------------------------------------
 
Title:
- --------------------------------------------------------------------------------
 
Address:
- --------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------
                                               (Zip Code)
 
Area Code and Telephone Number:
- ---------------------------------------------------------------------------
 
Dated: ____________ , 1998
 
DO NOT SEND NOTES WITH THIS FORM. ACTUAL SURRENDER OF NOTES MUST BE MADE
PURSUANT TO, AND BE ACCOMPANIED BY, AN EXECUTED LETTER OF TRANSMITTAL.
 
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                 INSTRUCTIONS FOR NOTICE OF GUARANTEED DELIVERY
 
     1. DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY. A properly completed and
duly executed copy of this Notice of Guaranteed Delivery and any other documents
required by this Notice of Guaranteed Delivery must be received by the Exchange
Agent at its address set forth herein prior to the Expiration Date. The method
of delivery of this Notice of Guaranteed Delivery and any other required
documents to the Exchange Agent is at the election and sole risk of the holder,
and the delivery will be deemed made only when actually received by the Exchange
Agent. If delivery is by mail, registered mail with return receipt requested,
properly insured, is recommended. As an alternative to delivery by mail, the
holder may wish to consider using an overnight or hand delivery service. In all
cases, sufficient time should be allowed to assure timely delivery. For a
description of the guaranteed delivery procedures, see Instruction 2 of the
Letter of Transmittal.
 
     2. SIGNATURES ON THIS NOTICE OF GUARANTEED DELIVERY. If this Notice of
Guaranteed Delivery is signed by the registered holder(s) of the Notes referred
to herein, the signature must correspond with the name(s) written on the face of
the Notes without alteration, enlargement, or any change whatsoever. If this
Notice of Guaranteed Delivery is signed by a participant of the Book-Entry
Transfer Facility whose name appears on a security position listing as the owner
of the Notes, the signature must correspond with the name shown on the security
position listing as the owner of the Notes.
 
     If this Notice of Guaranteed Delivery is signed by a person other than the
registered holder(s) of any Notes listed or a participant of the Book-Entry
Transfer Facility, this Notice of Guaranteed Delivery must be accompanied by
appropriate Notes powers, signed as the name of the registered holder(s) appears
on the Notes or signed as the name of the participant shown on the Book-Entry
Transfer Facility's security position listing. If this Notice of Guaranteed
Delivery is signed by a trustee, executor, administrator, guardian,
attorney-in-fact, officer of a corporation, or other person acting in a
fiduciary or representative capacity, such person should so indicate when
signing and submit with the Letter of Transmittal evidence satisfactory to the
Company of such person's authority to so act.
 
     3. REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES. Questions and requests for
assistance and requests for additional copies of the Prospectus may be directed
to the Exchange Agent at the address specified in the Prospectus. Holders may
also contact their broker, dealer, commercial bank, trust company, or other
nominee for assistance concerning the Exchange Offer.
 
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