Document and Entity Information	3 Months Ended
	Mar. 31, 2022 shares
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2022
Entity File Number	1-9328
Entity Registrant Name	ECOLAB INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-0231510
Entity Address, Address Line One	1 Ecolab Place
Entity Address, City or Town	St. Paul
Entity Address, State or Province	MN
Entity Address, Postal Zip Code	55102
City Area Code	800
Local Phone Number	232-6522
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	285,655,167
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000031462
Amendment Flag	false
COMMON STOCK
Title of 12(b) Security	Common Stock, $1.00 par value
Trading Symbol	ECL
Security Exchange Name	NYSE
2.625% Euro Notes due 2025
Title of 12(b) Security	2.625% Euro Notes due 2025
Trading Symbol	ECL 25
Security Exchange Name	NYSE
1.000% Euro Notes due 2024
Title of 12(b) Security	1.000% Euro Notes due 2024
Trading Symbol	ECL 24
Security Exchange Name	NYSE