Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 14, 2021
Document and Entity Information:
Entity Registrant Name	374WATER INC.
Document Type	10-Q
Document Period End Date	Mar. 31, 2021
Amendment Flag	false
Entity Central Index Key	0000933972
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		97,216,246
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Current Reporting Status	Yes
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Interactive Data Current	Yes
Entity File Number	000-27866
Entity Incorporation, State or Country Code	DE