Nitrate Water Contamination: Filtration Methods and Health Limits

Volume I  ·  May 2026  ·  220 words

Nitrate (NO3) in drinking water, primarily from agricultural fertilizer runoff and septic system leaching, is regulated by the EPA at a maximum contaminant level of 10 mg/L (as nitrogen). Above this level, nitrate interferes with the blood's oxygen-carrying capacity (methemoglobinemia), with infants under 6 months at highest risk. Nitrate is an anion — negatively charged — and is not removed by activated carbon or mechanical filtration. Reverse osmosis is the primary point-of-use removal technology, with rejection rates of 85-95% for nitrate. The APEC ROES-50 reduces nitrate to below detection limits in most feed water concentrations. Ion exchange — the same mechanism used by water softeners but with anion exchange resin — also removes nitrate, exchanging nitrate ions for chloride ions. Whole-house anion exchange systems are more expensive than point-of-use RO ($800-1,500 vs $200-400) but treat all household water. Testing is the prerequisite: nitrate is tasteless, odorless, and colorless, and the only way to know if it is present is through a certified laboratory test ($20-40). Private well owners should test for nitrate annually, particularly in agricultural areas.