Mercury in Drinking Water
EPA limits, health effects, and what to do if your water is affected.
🩨 Health Effects
Kidney damage from long-term exposure to inorganic mercury in drinking water. Mercury is best known for neurological effects from methylmercury in fish, but inorganic mercury in drinking water primarily affects the kidneys.
📍 Sources in Water
Enters water from industrial waste discharge, natural deposits, landfills, and cropland runoff. Coal-fired power plants and chlor-alkali plants are major industrial sources.
✅ What To Do
Reverse osmosis or granular activated carbon filters can reduce inorganic mercury. Mercury violations in public water systems are very rare.
📜 Regulation History
The EPA set the mercury MCL at 0.002 mg/L (2 ppb) in 1975 under the original National Interim Primary Drinking Water Regulations, and it has remained unchanged. The WHO guideline for inorganic mercury is 0.006 mg/L, less strict than the US standard.
🔬 How To Test Your Water
Certified lab tests for mercury in water cost $20-$40. Mercury requires specialized sample collection using preservatives provided by the lab. Home test kits for mercury are not widely available; lab testing is recommended for accurate results.
💧 Which Filters Remove Mercury?
Granular activated carbon (GAC) filters are effective against inorganic mercury, as are reverse osmosis systems (NSF/ANSI 58 certified). Look for NSF/ANSI 53 certification for mercury reduction. KDF media filters also reduce mercury levels.
Check your tap water for Mercury
Search your ZIP code to see if your water system has had Mercury 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.