Sec Form 4 Filing - Yeung William @ Energy Recovery, Inc. - 2021-02-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Yeung William 2. Issuer Name and Ticker or Trading Symbol Energy Recovery, Inc. [ ERII] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Legal Officer (Last) (First) (Middle) C/O ENERGY RECOVERY, 1717 DOOLITTLE DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 02/01/2021 (Street) SAN LEANDRO, CA94577 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock ( 1 ) ( 2 ) 02/01/2021 A 9,849 A $ 13.96 70,895 D Common Stock ( 3 ) 02/02/2021 F 4,878 D $ 13.9653 ( 4 ) 66,017 D Common Stock ( 3 ) 02/03/2021 F 1,182 D $ 13.8147 ( 5 ) 64,835 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Employee Stock Option (Right to Buy) $ 13.96 02/01/2021 A 26,336 ( 6 ) 02/01/2031 Common Stock 26,336 $ 0 26,336 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Yeung William C/O ENERGY RECOVERY 1717 DOOLITTLE DRIVE SAN LEANDRO, CA94577 Chief Legal Officer Signatures /s/ William Yeung 02/03/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each restricted stock unit represents the right to receive, at settlement, one (1) share of the Company's Common Stock. ( 2 )The restricted stock unit was granted on February 1, 2021 and vests 25% on each of the first four anniversaries of the grant date. ( 3 )Payment of tax obligation by selling securities incident to the vesting of securities in accordance with Rule 16b-3(e). ( 4 )This figure is the weighted average sales price of multiple trades ranging from $13.90 to $14.07 per share. 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. ( 5 )This figure is the weighted average sales price of multiple trades ranging from $13.78 to $13.95 per share. 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. ( 6 )This employee stock option was granted on February 1, 2021. 25% of the options will vest on the 1st anniversary of the grant date; thereafter, the remaining 75% vest 1/36th per month.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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