UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549



                                    FORM 8-K


                                 Current Report



                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934


        Date of Report (date of earliest event reported): August 16, 2004


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


<TABLE>
<CAPTION>
           <S>                                     <C>                              <C>

               Massachusetts                                1-7211                            04-2068530
          (State of incorporation)                 (Commission File Number)          (IRS Employer Identification
                                                                                                Number)

       65 Grove Street, Watertown, MA                       02472                            617-926-2500
  (Address of principal executive offices)                (Zip Code)                (Registrant's telephone number,
                                                                                         including area code)
</TABLE>

<PAGE>

ITEM 4.  CHANGES IN REGISTRANT'S CERTIFYING ACCOUNTANT

On August 16, 2004 the Audit Committee of the Board of Directors of Ionics,
Incorporated (the "Company") dismissed PricewaterhouseCoopers LLP as the
Company's independent registered public accounting firm, and engaged KPMG LLP as
the Company's new independent registered public accounting firm for the year
ending December 31, 2004. KPMG LLP had served as the independent accountants for
Ecolochem, Inc. and its affiliated companies, which were acquired by the Company
on February 13, 2004.

The reports issued by PricewaterhouseCoopers LLP on the consolidated financial
statements of the Company as of and for the years ended December 31, 2003 and
2002 did not contain an adverse opinion or disclaimer of opinion, nor were they
qualified or modified as to uncertainty, audit scope or accounting principle.

During the two years ended December 31, 2003 and 2002 and during the interim
period from January 1, 2004 to August 16, 2004, there have been no disagreements
between the Company and PricewaterhouseCoopers LLP on any matter of accounting
principles or practices, financial statement disclosure, or auditing scope or
procedure, which disagreements, if not resolved to PricewaterhouseCoopers LLP's
satisfaction, would have caused PricewaterhouseCoopers LLP to make reference to
the subject matter of the disagreements in its reports on the Company's
consolidated financial statements for such years.

During the two years ended December 31, 2003 and 2002 and during the interim
period from January 1, 2004 to August 16, 2004, there were no reportable events
as defined in Item 304(a)(1)(v) of Regulation S-K, except that in connection
with the audit of the Company's consolidated financial statements for the fiscal
year ended December 31, 2002, PricewaterhouseCoopers LLP identified certain
matters representing material weaknesses in the Company's internal controls over
financial reporting and discussed these matters with the Audit Committee. These
material weaknesses were disclosed in Item 14 of the Company's Annual Report on
Form 10-K for 2002. The Company took a number of corrective actions to address
these matters in 2003.

The Company has authorized PricewaterhouseCoopers LLP to respond fully to the
inquiries of KPMG LLP concerning any matters discussed above. The Company has
provided PricewaterhouseCoopers LLP with a copy of the above statements. The
Company has requested PricewaterhouseCoopers LLP to furnish a letter addressed
to the Securities and Exchange Commission stating whether PricewaterhouseCoopers
LLP agrees with the above statements and, if not, stating the respects in which
it does not agree. A copy of such letter from PricewaterhouseCoopers LLP, dated
August 18, 2004, is attached as Exhibit 16.1 to this Current Report on Form 8-K.

During the Company's two most recent fiscal years and through the date of this
Form 8-K, the Company has not consulted with KPMG LLP with respect to any of the
matters or reportable events set forth in Item 304(a)(2)(i) and (ii) of
Regulation S-K.





                                      -2-
<PAGE>



ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS

(c)      Exhibits

         16.1     Letter dated August 18, 2004 from PricewaterhouseCoopers LLP
                  to the Securities and Exchange Commission

         99.1     Press Release dated August 18, 2004



                                    SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

Date:  August 18, 2004                      IONICS, INCORPORATED
                                            (Registrant)


                                            By: /s/Daniel M. Kuzmak
                                                -----------------------
                                                 Daniel M. Kuzmak
                                                 Chief Financial Officer



                                  EXHIBIT INDEX

Exhibit Number         Description
--------------         -----------

   16.1                Letter dated August 18, 2004 from PricewaterhouseCoopers
                       LLP to the Securities and Exchange Commission

   99.1                Press Release dated August 18, 2004



                                      -3-
<PAGE>



                                                                   Exhibit 16.1


August 18, 2004

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549

Commissioners:

We have read the statements made by Ionics, Incorporated (copy attached), which
we understand will be filed with the Commission, pursuant to Item 4 of Form 8-K,
as part of the Company's Form 8-K report dated August 16, 2004. We agree with
the statements concerning our Firm in such Form 8-K.


Very truly yours,



/s/ PRICEWATERHOUSECOOPERS LLP
------------------------------
PricewaterhouseCoopers LLP



                                      -4-
<PAGE>



                                                                   Exhibit 99.1

             IONICS, INCORPORATED APPOINTS NEW INDEPENDENT AUDITORS


Watertown, MA, August 18, 2004 . . . Ionics, Incorporated (NYSE-ION) announced
today that it was changing its independent auditors from PricewaterhouseCoopers
LLP ("PWC") to KPMG LLP ("KPMG").

Douglas R. Brown, Ionics' Chief Executive Officer, stated, "When Ionics acquired
Ecolochem earlier this year, we undertook an evaluation of the service
capabilities of both PWC, our existing auditor, and KPMG, who had been
Ecolochem's auditor for nearly 19 years. Clearly, PWC and its predecessor
Coopers & Lybrand have provided Ionics with many years of dedicated and highly
professional service. However, after a thorough review, we concluded that KPMG's
experience and capabilities would better serve Ionics' long-term needs. Having
been Ecolochem's independent auditors for so long, they clearly understand the
water services model we are trying to build. We look forward to creating as
successful a relationship with KPMG as we have had with PWC."

Doug Brown further stated, "We take the decision to change our independent
auditors very seriously. Ultimately, we believe switching to KPMG is in the
Company's and our shareholders' best interests."

KPMG will serve as Ionics' independent auditors for the fiscal year ending
December 31, 2004.


About Ionics, Inc.
Ionics is a global leader in water purification and wastewater treatment. The
Company has over 50 years of experience in the design, installation, operation
and maintenance of water and wastewater treatment systems and is a leading
provider of emergency and long-term water treatment services. More
membrane-based desalination systems have been designed and built by Ionics than
any other supplier worldwide. Ionics is also a leader in supplying
zero-liquid-discharge systems, in providing ultrapure water systems for the
power and microelectronics industries, and in the measurement and analysis of
water impurities. The Company also supplies Point-of-Use and Point-of-Entry
water treatment systems for commercial and residential applications. For more
information, visit www.ionics.com.



                                                               # # # # #


For more information, contact:
<TABLE>
<CAPTION>
<S>                                                                   <C>
John F. Curtis                                                        Daniel M. Kuzmak
Vice President, Strategy and Operations, Treasurer                    Vice President, Chief Financial Officer
Ionics, Incorporated                                                  Ionics, Incorporated
Tel: (617) 673-4403                                                   Tel: (617) 673-4350
jcurtis@ionics.com                                                    dkuzmak@ionics.com

</TABLE>
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UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549

                                    FORM 8-K

                                 Current Report

                       Pursuant to Section 13 or 15(d) of
                       The Securities Exchange Act of 1934

        Date of Report (date of earliest event reported): August 16, 2004

                              IONICS, INCORPORATED
             (Exact name of registrant as specified in its charter)
Massachusetts                                1-7211                            04-2068530
          (State of incorporation)                 (Commission File Number)          (IRS Employer Identification
                                                                                                Number)

       65 Grove Street, Watertown, MA                       02472                            617-926-2500
  (Address of principal executive offices)                (Zip Code)                (Registrant's telephone number,
                                                                                         including area code)
ITEM 4.  CHANGES IN REGISTRANT'S CERTIFYING ACCOUNTANT

On August 16, 2004 the Audit Committee of the Board of Directors of Ionics,
Incorporated (the "Company") dismissed PricewaterhouseCoopers LLP as the
Company's independent registered public accounting firm, and engaged KPMG LLP as
the Company's new independent registered public accounting firm for the year
ending December 31, 2004. KPMG LLP had served as the independent accountants for
Ecolochem, Inc. and its affiliated companies, which were acquired by the Company
on February 13, 2004.

The reports issued by PricewaterhouseCoopers LLP on the consolidated financial
statements of the Company as of and for the years ended December 31, 2003 and
2002 did not contain an adverse opinion or disclaimer of opinion, nor were they
qualified or modified as to uncertainty, audit scope or accounting principle.

During the two years ended December 31, 2003 and 2002 and during the interim
period from January 1, 2004 to August 16, 2004, there have been no disagreements
between the Company and PricewaterhouseCoopers LLP on any matter of accounting
principles or practices, financial statement disclosure, or auditing scope or
procedure, which disagreements, if not resolved to PricewaterhouseCoopers LLP's
satisfaction, would have caused PricewaterhouseCoopers LLP to make reference to
the subject matter of the disagreements in its reports on the Company's
consolidated financial statements for such years.

During the two years ended December 31, 2003 and 2002 and during the interim
period from January 1, 2004 to August 16, 2004, there were no reportable events
as defined in Item 304(a)(1)(v) of Regulation S-K, except that in connection
with the audit of the Company's consolidated financial statements for the fiscal
year ended December 31, 2002, PricewaterhouseCoopers LLP identified certain
matters representing material weaknesses in the Company's internal controls over
financial reporting and discussed these matters with the Audit Committee. These
material weaknesses were disclosed in Item 14 of the Company's Annual Report on
Form 10-K for 2002. The Company took a number of corrective actions to address
these matters in 2003.

The Company has authorized PricewaterhouseCoopers LLP to respond fully to the
inquiries of KPMG LLP concerning any matters discussed above. The Company has
provided PricewaterhouseCoopers LLP with a copy of the above statements. The
Company has requested PricewaterhouseCoopers LLP to furnish a letter addressed
to the Securities and Exchange Commission stating whether PricewaterhouseCoopers
LLP agrees with the above statements and, if not, stating the respects in which
it does not agree. A copy of such letter from PricewaterhouseCoopers LLP, dated
August 18, 2004, is attached as Exhibit 16.1 to this Current Report on Form 8-K.

During the Company's two most recent fiscal years and through the date of this
Form 8-K, the Company has not consulted with KPMG LLP with respect to any of the
matters or reportable events set forth in Item 304(a)(2)(i) and (ii) of
Regulation S-K.

                                      -2-
ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS

(c)      Exhibits

         16.1     Letter dated August 18, 2004 from PricewaterhouseCoopers LLP
                  to the Securities and Exchange Commission

         99.1     Press Release dated August 18, 2004

                                    SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

Date:  August 18, 2004                      IONICS, INCORPORATED
                                            (Registrant)

                                            By: /s/Daniel M. Kuzmak
                                                -----------------------
                                                 Daniel M. Kuzmak
                                                 Chief Financial Officer

                                  EXHIBIT INDEX

Exhibit Number         Description
--------------         -----------

   16.1                Letter dated August 18, 2004 from PricewaterhouseCoopers
                       LLP to the Securities and Exchange Commission

   99.1                Press Release dated August 18, 2004

                                      -3-
Exhibit 16.1

August 18, 2004

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549

Commissioners:

We have read the statements made by Ionics, Incorporated (copy attached), which
we understand will be filed with the Commission, pursuant to Item 4 of Form 8-K,
as part of the Company's Form 8-K report dated August 16, 2004. We agree with
the statements concerning our Firm in such Form 8-K.

Very truly yours,

/s/ PRICEWATERHOUSECOOPERS LLP
------------------------------
PricewaterhouseCoopers LLP

                                      -4-
Exhibit 99.1

             IONICS, INCORPORATED APPOINTS NEW INDEPENDENT AUDITORS

Watertown, MA, August 18, 2004 . . . Ionics, Incorporated (NYSE-ION) announced
today that it was changing its independent auditors from PricewaterhouseCoopers
LLP ("PWC") to KPMG LLP ("KPMG").

Douglas R. Brown, Ionics' Chief Executive Officer, stated, "When Ionics acquired
Ecolochem earlier this year, we undertook an evaluation of the service
capabilities of both PWC, our existing auditor, and KPMG, who had been
Ecolochem's auditor for nearly 19 years. Clearly, PWC and its predecessor
Coopers & Lybrand have provided Ionics with many years of dedicated and highly
professional service. However, after a thorough review, we concluded that KPMG's
experience and capabilities would better serve Ionics' long-term needs. Having
been Ecolochem's independent auditors for so long, they clearly understand the
water services model we are trying to build. We look forward to creating as
successful a relationship with KPMG as we have had with PWC."

Doug Brown further stated, "We take the decision to change our independent
auditors very seriously. Ultimately, we believe switching to KPMG is in the
Company's and our shareholders' best interests."

KPMG will serve as Ionics' independent auditors for the fiscal year ending
December 31, 2004.

About Ionics, Inc.
Ionics is a global leader in water purification and wastewater treatment. The
Company has over 50 years of experience in the design, installation, operation
and maintenance of water and wastewater treatment systems and is a leading
provider of emergency and long-term water treatment services. More
membrane-based desalination systems have been designed and built by Ionics than
any other supplier worldwide. Ionics is also a leader in supplying
zero-liquid-discharge systems, in providing ultrapure water systems for the
power and microelectronics industries, and in the measurement and analysis of
water impurities. The Company also supplies Point-of-Use and Point-of-Entry
water treatment systems for commercial and residential applications. For more
information, visit www.ionics.com.

                                                               # # # # #

For more information, contact:
John F. Curtis                                                        Daniel M. Kuzmak
Vice President, Strategy and Operations, Treasurer                    Vice President, Chief Financial Officer
Ionics, Incorporated                                                  Ionics, Incorporated
Tel: (617) 673-4403                                                   Tel: (617) 673-4350
jcurtis@ionics.com                                                    dkuzmak@ionics.com