Arsenic in Drinking Water
EPA limits, health effects, and what to do if your water is affected.
🩨 Health Effects
Long-term exposure is linked to skin damage, circulatory problems, and increased risk of bladder, lung, and skin cancer. Arsenic also affects the nervous system and can contribute to diabetes. The EPA lowered the MCL from 0.05 to 0.01 mg/L in 2001 in response to cancer evidence.
📍 Sources in Water
Arsenic occurs naturally in rock and soil and dissolves into groundwater, making it most common in private and small community wells. Mining operations, agricultural pesticides, and industrial discharge can also elevate levels. Naturally high concentrations are found in parts of the Southwest, New England, and upper Midwest.
✅ What To Do
Use a point-of-use reverse osmosis (RO) filter or activated alumina filter, both rated NSF/ANSI 53 for arsenic removal. Boiling water does not remove arsenic. Check your utility's Consumer Confidence Report for measured levels.
📜 Regulation History
The EPA first regulated arsenic in 1975 at 0.05 mg/L, then lowered the MCL to 0.01 mg/L (10 ppb) in January 2001 after extensive debate over cancer risk, with compliance required by 2006. The WHO guideline is also 0.01 mg/L. New Jersey has adopted a stricter state MCL of 0.005 mg/L (5 ppb).
🔬 How To Test Your Water
Certified lab tests for arsenic cost $15-$40 and require a water sample collected in a lab-provided container. Home test kits for arsenic are available for $10-$30 but are less accurate than lab analysis. Testing should distinguish between arsenic III and arsenic V forms, as treatment effectiveness varies by species.
💧 Which Filters Remove Arsenic?
Reverse osmosis (NSF/ANSI 58 certified) removes 80-95% of arsenic and is the most practical home solution. Activated alumina filters and iron-based adsorptive media are also effective, particularly for arsenic V. Standard activated carbon filters are not effective against arsenic; look specifically for NSF/ANSI 53 certification for arsenic reduction.
Check your tap water for Arsenic
Search your ZIP code to see if your water system has had Arsenic violations, plus lead testing results and an overall safety grade.
Search your ZIP code →Data from the EPA's Safe Drinking Water Information System (SDWIS). MCLs reflect minimum federal standards; some contaminants may pose health risks below these thresholds.