ClO4
Perchlorate
emerging contaminantSDWA code: 4010
EPA Limit (MCL)
56 ppt (0.000056 mg/L)
Health Goal (MCLG)
56 ppt (0.000056 mg/L)
Unit of Measure
mg/L
How concentrations are reported
EPA finalized an MCL of 0.056 mg/L (56 micrograms per liter) in 2024.
Health Effects
Disrupts thyroid hormone production; may affect metabolism, growth, and development. Particularly concerning for pregnant women and infants.
How It Gets Into Water
Leaching from explosives, rocket propellants, and fireworks manufacturing; naturally occurring in some arid regions
Official EPA Guidance
For authoritative information on Perchloratein drinking water, visit the EPA's official resource page.
View EPA Guidance ↗