Exhibit 10.5 

IONICS, INCORPORATED 

2003 NON-EMPLOYEEDIRECTORS STOCK OPTION PLAN 

    1.                 *Purpose.*This Non-Qualified Stock Option Plan, to be known as the 2003          Non-Employee Directors Stock Option Plan (hereinafter, the “Plan”) is          intended to promote the interests of IONICS, INCORPORATED (hereinafter, the          “Company”) by providing an inducement to obtain and retain the          services of qualified persons who are not employees or officers of the Company          or of any entity whose controlling stock or other ownership interest is owned          directly or indirectly by the Company (each such entity, a          “Subsidiary”)to serve as members of the Board of Directors of the          Company (the “Board”). 

    2.                 *Available Shares.*The total number of shares of Common Stock, par value          $1.00 per share, of the Company (the “Common Stock”) for which options          may be granted under the Plan (hereinafter called “Options” and each          singly an “Option”) shall not exceed 200,000 shares, subject to          adjustment in accordance with Section 10 of the Plan. Shares issued under the          Plan may consist in whole or in part of authorized but unissued shares or          treasury shares. If any Options granted under the Plan are surrendered before          exercise or lapse without exercise, in whole or in part, the shares reserved          therefor shall again be available for the grant of Options under the Plan. 

    3.                 *Administration.*The Plan shall be administered by the Board or, to the          extent permitted by applicable law, by a committee appointed by the Board (the          Committee”). In the event the Board fails to appoint or refrains from          appointing a Committee, the Board shall have all power and authority to          administer the Plan. In such event, the word “Committee” wherever used          herein shall be deemed to mean the Board. The Committee shall, subject to the          provisions of the Plan, have the power to construe the Plan, to determine all          questions hereunder, and to adopt, amend and repeal such rules and regulations          for the administration of the Plan as it may deem desirable. No member of the          Board or the Committee shall be liable for any action or determination made in          good faith with respect to the Plan or any Option granted under it. 

    4.                 *Eligibility: Automatic Grant of Options.*Only persons who hold office as          members of the Board and who are not otherwise employees of the Company or of          any Subsidiary (each a “Non-Employee Director”) may be granted an          Option under this Plan. The term “Optionee” as used in this Plan means          a Non-Employee Director to whom an Option has been granted under the Plan.          Subject to the availability of shares of Common Stock under the Plan, each          Non-Employee Director who is either elected to the Board at the 2003 annual          meeting of stockholders of the Company (the “2003 Annual Meeting”)or          who continues as a member of the Board following the 2003 Annual Meeting, shall          automatically be granted, without further action by the Committee, an initial          Option to acquire 4,000 shares of Common Stock under the Plan immediately          following the 2003 Annual Meeting, and an additional Option to acquire 2,000          shares of Common Stock immediately upon completion of each next successive year          in office. Subject to availability of shares of Common Stock under the Plan,          each Non-Employee Director who is initially elected as a member of the Board          after the 2003 Annual Meeting, shall be automatically granted, without further          action by the Committee, an Option to acquire 2,000 shares of Common Stock under          the Plan immediately after the annual meeting of the stockholders of the Company          at which he or she is first elected a member of the Board, and an additional          Option to acquire 2,000 shares of Common Stock immediately upon completion of          each next successive year in office. A Non-Employee Director who assumes office          at a time other than at the time of the Company’s annual meeting of          stockholders shall be treated for purposes of the preceding sentence as having          been first elected as a member of the Board at the Company’s annual meeting          of stockholders next following his or her assumption of office. For purposes of          the Plan, a Non-Employee Director shall be considered to have completed a          “year in office” on the date of each annual meeting of stockholders of          the Company while he or she continues in office; provided, however, that if the          interval between any two such annual meetings is greater than 395 days, a          Non-Employee Director shall be considered to have completed a “year in          office” for purposes of the Plan on the 395th day after the preceding          year’s annual meeting of stockholders of the Company, rather than on the          date of the second of the two such annual meetings. 

        TheOptions to be granted under this Section 4 shall be the only Options to be granted at anytime to a Non-Employee Director under the Plan. The number of shares of Common Stockcovered by Options granted under this Section 4 shall be subject to adjustment inaccordance with the provisions of Section 10 of the Plan. Notwithstanding anything to thecontrary set forth herein, if this Plan is not approved by the affirmative vote of theholders of a majority of the shares of Common Stock present in person or by proxy andvoting on such matter at a meeting within twelve (12) months of the date it is approved bythe Board, then the Plan and the Options granted pursuant to this Section 4 shallterminate and become void, and no further Options shall be granted under the Plan. 

    5.                 *Option Price.*The purchase price of the Common Stock covered by an Option          granted pursuant to the Plan shall be 100%of the fair market value of such          shares on the day the Option is granted. The option price will be subject to          adjustment in accordance with the provisions of Section 10 of the Plan. For          purposes of the Plan, if, at the time an option is granted under the Plan, the          Company’s Common Stock is publicly traded, “fair market value”          shall mean the last price for the Common Stock on the New York Stock Exchange          (or any other national securities exchange on which such shares are then traded)          on the trading day next preceding the date of grant of an Option. If the Common          Stock is not publicly traded at the time an option is granted under the Plan,          “fair market value” shall be deemed to be the fair value of the Common          Stock as determined by the Committee after taking into consideration all factors          which it deems appropriate.