X0306 4 2020-02-03 0001421517 Energy Recovery, Inc. ERII 0001751098 Ballard Joshua C/O ENERGY RECOVERY, INC. 1717 DOOLITTLE DRIVE SAN LEANDRO CA 94577 1 Chief Financial Officer Common Stock 2020-02-03 4 F 0 2198 10.2525 D 19883 D Payment of tax obligation by selling securities incident to the vesting of securities in accordance with Rule 16b-3(e). Represents the weighted average stock price of the shares sold to cover tax obligation for restricted stock unit award vesting. The Reporting Person undertakes to provide the SEC staff, ERI or a shareholder of ERI full information about the number of shares sold at each separate price upon request. /s/ William Yeung, Attorney-in-Fact for Joshua Ballard 2020-02-05