High nitrates in well water — typically from fertilizer runoff or septic systems — are a serious health risk for infants and pregnant women. Ion exchange removes them effectively.
Nitrates are one of the most common well water contaminants in agricultural regions. They enter groundwater through fertilizer application, animal waste, and failing septic systems. The EPA maximum contaminant level (MCL) for nitrates is 10 mg/L (ppm) — a level set specifically to protect against 'blue baby syndrome' (methemoglobinemia), a potentially fatal condition in infants under 6 months caused by nitrates reducing the blood's ability to carry oxygen.
Standard carbon block filters do not remove nitrates. Effective nitrate reduction requires ion exchange with nitrate-selective resin, reverse osmosis, or distillation. If you have well water in an agricultural area, nitrate testing should be a regular part of your water maintenance schedule.