Selenium in Drinking Water
EPA limits, health effects, and what to do if your water is affected.
🩨 Health Effects
Selenium is an essential trace element, but at high levels causes selenosis: hair and fingernail loss, numbness in fingers and toes, circulatory problems, and possible nerve damage.
📍 Sources in Water
Occurs naturally in certain soils and rock. High natural levels are found in the Great Plains and interior West. Also enters water from mining operations, oil refineries, and agricultural drainage.
✅ What To Do
Reverse osmosis and distillation are effective at reducing selenium. Ion exchange filters also work. Check your utility's Consumer Confidence Report.
📜 Regulation History
The EPA set the selenium MCL at 0.01 mg/L in 1975, then raised it to 0.05 mg/L (50 ppb) in 1991 after reassessing the health data and recognizing selenium as an essential nutrient at low levels. The WHO guideline is 0.04 mg/L, slightly stricter than the US standard.
🔬 How To Test Your Water
Certified lab tests for selenium cost $15-$30. Home test kits for selenium are not commonly available. A comprehensive inorganics panel from a certified lab ($50-$80) will include selenium along with other metals and minerals.
💧 Which Filters Remove Selenium?
Reverse osmosis (NSF/ANSI 58 certified) removes 90%+ of selenium. Distillation and strong-base anion exchange also work well. Activated carbon filters are not effective against selenium. Look for NSF/ANSI 58 certification with a specific selenium reduction claim.
Check your tap water for Selenium
Search your ZIP code to see if your water system has had Selenium 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.