Giar
Giardia lamblia
microbialSDWA code: 3001
EPA Limit (MCL)
No MCL
Health Goal (MCLG)
Zero (0)
No level is considered safe
Unit of Measure
cysts/L
How concentrations are reported
Regulated under the Surface Water Treatment Rule (SWTR). Systems must achieve 99.9% (3-log) removal or inactivation.
Health Effects
Giardiasis: diarrhea, gas, greasy stools, stomach cramps. Symptoms may last 2-6 weeks. Can cause chronic digestive issues.
The EPA has set the health goal (MCLG) at zero, meaning no level of exposure is considered risk-free.
How It Gets Into Water
Human and animal fecal waste; beavers and other wild animals are common reservoirs; surface water contamination
Official EPA Guidance
For authoritative information on Giardia lambliain drinking water, visit the EPA's official resource page.
View EPA Guidance ↗