X0306 4 2021-03-01 0001421517 Energy Recovery, Inc. ERII 0001668422 Clemente Rodney C/O ENERGY RECOVERY, INC. 1717 DOOLITTLE DRIVE SAN LEANDRO CA 94577 1 SVP, Water Common Stock 2021-03-01 4 M 0 9957 18.19 A 52191 D Common Stock 2021-03-01 4 S 0 9957 18.19 D 42234 D Common Stock 2021-03-01 4 M 0 10998 18.19 A 53232 D Common Stock 2021-03-01 4 S 0 10998 18.19 D 42234 D Common Stock 2021-03-01 4 M 0 7327 18.2103 A 49561 D Common Stock 2021-03-01 4 S 0 7327 18.2103 D 42234 D Common Stock 2021-03-02 4 M 0 912 18.3289 A 43146 D Common Stock 2021-03-02 4 S 0 912 18.3289 D 42234 D Employee Stock Option (Right to Buy) 10.19 2021-03-01 4 M 0 9957 0 D 2027-02-02 Common Stock 9957 0 D Employee Stock Option (Right to Buy) 10.19 2021-03-01 4 M 0 10998 0 D 2027-02-02 Common Stock 10998 912 D Employee Stock Option (Right to Buy) 10.21 2021-03-01 4 M 0 7327 0 D 2030-01-31 Common Stock 18287 610 D Employee Stock Option (Right to Buy) 10.19 2021-03-02 4 M 0 912 0 D 2027-02-02 Common Stock 912 0 D This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person on December 14, 2020. This figure is the weighted average sales price of multiple trades. 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. This employee stock option was granted on February 2, 2017. All of the options are fully vested and exercisable. This employee stock option was granted on January 31, 2020. 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 2021-03-03