X0306 4/A 2019-01-31 2019-02-05 0001421517 Energy Recovery, Inc. ERII 0001668422 Clemente Rodney C/O ENERGY RECOVERY 1717 DOOLITTLE DRIVE SAN LEANDRO CA 94577 1 VP, Water Common Stock 2019-01-31 4 A 0 21381 7.60 A 65114 D Common Stock 2019-02-05 4 F 0 1308 8.39990 D 63806 D Common Stock 2019-02-04 4 F 0 1655 7.7586 D 62151 D Common Stock 2019-02-05 4 F 0 1212 7.79550 D 60939 D Employee Stock Option (Right to Buy) 7.60 2019-01-31 4 A 0 35800 0 A 2029-01-31 Common Stock 35800 35800 D Each restricted stock unit represents the right to receive, at settlement, one (1) share of the Company's Common Stock. The restricted stock unit award was granted on January 31, 2019 and vests 25% on each of the first four anniversaries of the grant date. Payment of tax obligation by withholding securities incident to the vesting of the securities in accordance with Rule 16b-3(e). Represents the weighted average stock price of the shares withheld to cover the tax obligation for each restricted stock unit award vesting. 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 the tax obligation for restricted stock unit award vesting. This employee stock option was granted on January 31, 2019. 25% of the options will vest on the 1st anniversary of the grant date; thereafter, the remaining 75% vest 1/36th per month. /s/ William Yeung, Attorney-in-Fact for Rodney Clemente 2019-03-18