THIRD AMENDMENT TO EXECUTIVE EMPLOYMENT AGREEMENT

Exhibit 10.7.3

THIRD AMENDMENT TO EXECUTIVE EMPLOYMENT AGREEMENT

This Third Amendment to the Executive Employment Agreement of G.G. Pique (“Third Amendment”) is made as of December 31, 2008 (“Third Amendment Effective Date”) by and between Energy Recovery, Inc., a Delaware corporation, with its principal offices at 1908 Doolittle Drive, San Leandro, CA 94577 (the “Company” and G.G. Pique, an individual (the “Executive”) ( together, the “Parties”) in order to satisfy the requirements of Section 409A of the Internal Revenue Code of 1986, as amended and the Treasury Regulations promulgated thereunder, as amended.

Pursuant to Article 5.8 of the Executive Employment Agreement, the Company hereby amends that Agreement, including any amendment thereto, as follows:

Article 2.2 . The Company amends Article 2.2 by adding the following sentence to the end thereof:

All reimbursements shall be made in accordance with the requirements with the short-term deferral exemption to Section 409A of the Code such that all expenses are submitted and reimbursed no later that March 15th of the year following the year in which such expenses are incurred.

Article 3.2(b)(iv) . The Company amends Article 3.2(b)(iv) by replacing the last sentence thereof as follows:

However, no amount payable under this Agreement that is non-qualified deferred compensation subject to Section 409A of the Code, as determined in the sole discretion of the Company, shall be paid unless the Executive experiences a termination that is also a “separation from service” within the meaning of Section 409A of the Code (a “Separation from Service”), and, if the Executive is a “specified employee” within the meaning of Section 409A of the Code as of the date of the Separation from Service (as determined in accordance with Section 409A of the Code), su