Drinking Water Contaminants

EPA limits, health effects, and safety information for 56 regulated and monitored contaminants found in US drinking water. Click any contaminant to learn more, then search your ZIP to check your local water.

MCL: 0.015 mg/L

MCL: 0.005 mg/L

MCL: 0.002 mg/L

MCL: 0.002 mg/L

MCL: 0.006 mg/L

MCL: 0.004 mg/L

Secondary Standard

Secondary Standard

Total Trihalomethanes (TTHMs)

Disinfection Byproduct

Haloacetic Acids (HAA5)

Disinfection Byproduct

Chlorine Dioxide

Combined Radium

Gross Alpha Activity

MCL: 0.005 mg/L

Volatile Organic

Trichloroethylene (TCE)

MCL: 0.005 mg/L

Volatile Organic

Tetrachloroethylene (PCE/PERC)

MCL: 0.005 mg/L

Volatile Organic

MCL: 0.002 mg/L

Volatile Organic

Methylene Chloride

MCL: 0.005 mg/L

Volatile Organic

Volatile Organic

Xylenes (Total)

Volatile Organic

Volatile Organic

Volatile Organic

Disinfection Byproduct

MCL: 0.003 mg/L

MCL: 0.002 mg/L

Polychlorinated Biphenyls (PCBs)

MCL: 0.0005 mg/L

Synthetic Organic

MCL: 0.002 mg/L

Dioxin (2,3,7,8-TCDD)

Synthetic Organic

MCL: 0.003 mg/L

DBCP (1,2-Dibromo-3-chloropropane)

MCL: 0.0002 mg/L

Ethylene Dibromide (EDB)

MCL: 0.00005 mg/L

MCL: 0.004 mg/L

PFAS (Per- and Polyfluoroalkyl Substances)

MCL: 4e-9 mg/L (PFOA/PFOS)

Emerging Contaminant

MCL: 0.000056 mg/L

Hexavalent Chromium (Chromium-6)