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 OF SECURITIES 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 * Hanstveit Arve   2. Issuer Name and Ticker or Trading Symbol Energy Recovery, Inc. [ERII] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ENERGY RECOVERY, INC., 1717 DOOLITTLE DRIVE 3. Date of Earliest Transaction (Month/Day/Year) 03/12/2019 (Street) SAN LEANDRO, CA 94577 4. If Amendment, Date Original Filed(Month/Day/Year) 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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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 03/12/2019   M   39,042 A $ 2.61 1,134,842 D   Common Stock 03/12/2019   S   39,042 D $ 8.2818 (1) 1,095,800 D   Common Stock 03/13/2019   M   100,000 A $ 7.31 1,195,800 D   Common Stock 03/13/2019   S   100,000 D $ 8.5873 (2) 1,095,800 D

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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 (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

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 (Month/Day/Year)

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)

$ 2.61

03/12/2019

M

39,042

(3)

09/16/2021

Common Stock

39,042

$ 0

0

D

Employee Stock Option (Right to Buy)

$ 7.31

03/13/2019

M

100,000

(4)

04/03/2019

Common Stock

100,000

$ 0

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Hanstveit Arve C/O ENERGY RECOVERY, INC. 1717 DOOLITTLE DRIVE SAN LEANDRO, CA 94577	X

Signatures

/s/ William Yeung, Attorney-in-Fact for Arve Hanstveit		03/14/2019
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	This figure is the weighted average sales price of multiple trades ranging from $8.2500 to $8.5000 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.
(2)	This figure is the weighted average sales price of multiple trades ranging from $8.3000 to $8.7700 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.
(3)	This employee stock option was granted on September 16, 2011. All of the options are fully vested and exercisable.
(4)	This employee stock option was granted on April 3, 2009. All of the options are fully vested and exercisable.

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