| Cover | Jul. 07, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 7, 2021 |
| Entity File Number | 000-27866 |
| Entity Registrant Name | 374WATER INC. |
| Entity Central Index Key | 0000933972 |
| Entity Tax Identification Number | 88-0271109 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 9300 S. Dadeland Blvd |
| Entity Address, Address Line Two | Suite 600 |
| Entity Address, City or Town | Miami |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33156 |
| City Area Code | (305) |
| Local Phone Number | 670-3370 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | PWVI |
| Security Exchange Name | NONE |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
