Sec Form 4 Filing - Gannon Chris M @ 374Water Inc. - 2024-04-22

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 Gannon Chris M 2. Issuer Name and Ticker or Trading Symbol 374Water Inc. [ SCWO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Executive Officer (Last) (First) (Middle) C/O 374 WATER INC., 100 SOUTHCENTER COURT, SUITE 200 3. Date of Earliest Transaction (MM/DD/YY) 04/22/2024 (Street) MORRISVILLE, NC27560 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 (restricted stock units) 04/22/2024 A 1,000,000 ( 1 ) A $ 0 1,120,000 ( 2 ) D Common Stock (restricted stock units) 08/28/2025 A 1,250,000 ( 3 ) A $ 0 2,370,000 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 Restricted Stock Units $ 0 04/22/2024 A 1,250,000 ( 1 ) ( 4 ) ( 4 ) Common Stock, $0.0001 par value 1,250,000 $ 0 1,250,000 ( 2 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Gannon Chris M C/O 374 WATER INC. 100 SOUTHCENTER COURT, SUITE 200 MORRISVILLE, NC27560 Chief Executive Officer Signatures /s/ Chris M. Gannon 09/02/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Restricted Stock Units (the "2024 RSUs") reported herein were granted to the Reporting Person on April 22, 2024, pursuant to his Employment Agreement (the "Employment Agreement"), dated as of April 19, 2024, and effective as of April 22, 2024 (the "Effective Date"). 250,000 of the shares subject to the 2024 RSUs vested on April 22, 2025, and the remaining 750,000 shares vest in equal increments on the last day of every month thereafter over the following 36 months, subject to the Reporting Person's continued employment with the Issuer on each vesting date. As of September 2, 2025, 333,333 shares subject to the 2024 RSUs were vested, and 666,667 shares are unvested. ( 2 )On May 1, 2024, the Reporting Person inadvertently filed a Form 3 that reported the RSUs. This filing serves to disclose the RSUs on a Form 4. ( 3 )The shares subject to the Restricted Stock Unit vest in equal increments on the last day of every month over 36 months, beginning on March 31, 2025, subject to the Reporting Person's continued employment with the Issuer on each vesting date. ( 4 )Under the Employment Agreement and subject to the terms of the Issuer's 2021 Equity Incentive Plan (the "Plan"), the Reporting Person was granted up 1,250,000 RSUs under the Plan, that vest pursuant to certain milestones set forth by the Issuer.

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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