| Cover | Jun. 13, 2022 |
| Cover [Abstract] | |
| Entity Registrant Name | 374WATER INC. |
| Entity Central Index Key | 0000933972 |
| Document Type | 8-K |
| Amendment Flag | false |
| Entity Emerging Growth Company | true |
| Document Period End Date | Jun. 13, 2022 |
| Entity Ex Transition Period | false |
| Entity Incorporation State Country Code | DE |
| Entity Tax Identification Number | 88-0271109 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity File Number | 000-27866 |
| Entity Address Address Line 1 | 701 W Main Street |
| Entity Address Address Line 2 | Suite 410 |
| Entity Address City Or Town | Durham |
| Entity Address Postal Zip Code | 27701 |
| City Area Code | 919 |
| Local Phone Number | 888-8194 |
| Security 12b Title | Common Stock, par value $0.001 |
| Trading Symbol | SCWO |
| Security Exchange Name | NASDAQ |
| Entity Address State Or Province | NC |
