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 * Pique Gonzalo G   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 __X__ Officer (give title below) _____ Other (specify below) President, CEO (Last) (First) (Middle) C/O ENERGY RECOVERY, INC., 1908 DOOLITTLE DRIVE 3. Date of Earliest Transaction (Month/Day/Year) 03/25/2009 (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 03/25/2009   S(1)   900 D $ 6.98 399,100 I By The Pique Bachman Income Security Trust Common Stock 03/25/2009   S   4,400 D $ 7 394,700 I By The Pique Bachman Income Security Trust Common Stock 03/25/2009   S   100 D $ 7.01 394,600 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   400 D $ 7.01 394,200 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   100 D $ 7.025 394,100 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,000 D $ 7.03 393,100 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   400 D $ 7.035 392,700 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   200 D $ 7.04 392,500 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,000 D $ 7.06 391,500 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   400 D $ 7.07 391,100 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,200 D $ 7.08 389,900 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,700 D $ 7.1 388,200 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   800 D $ 7.11 387,400 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,399 D $ 7.12 386,001 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   100 D $ 7.125 385,901 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   700 D $ 7.13 385,201 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   200 D $ 7.135 385,001 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,000 D $ 7.14 384,001 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1,816 D $ 7.15 382,185 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   300 D $ 7.16 381,885 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   400 D $ 7.2 381,485 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   100 D $ 7.205 381,385 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   100 D $ 7.21 381,285 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   1 D $ 7.24 381,284 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   299 D $ 7.25 380,985 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   500 D $ 7.27 380,485 I By The Pique Bachman Income Security Trust Common Stock 03/26/2009   S   485 D $ 7.28 380,000 I By The Pique Bachman Income Security Trust Common Stock 03/25/2009   S   900 D $ 6.98 399,100 I By The Pique Bachman Income Security Trust Common Stock               161,000 D

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

$ 2.65

(2)

12/08/2016

Common Stock

250,000

0

D

Warrant (Right to Buy)

$ 1

(3)

11/01/2015

Common Stock

150,000

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Pique Gonzalo G C/O ENERGY RECOVERY, INC. 1908 DOOLITTLE DRIVE SAN LEANDRO, CA 94577	X		President, CEO

Signatures

/s/Carolyn Bostick, attorney-in-fact for Gonzalo G. Pique		03/27/2009
**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)	The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 15, 2008.
(2)	All shares vest 1/4th on the one year anniversary of the vesting commencement date of 12/09/06 and 1/36th monthly thereafter.
(3)	All shares exercisable as of the warrant date of 11/01/2005.
Remarks: Exhibit 24 -- Power of Attorney

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