Nitrate (as N)
Nutrient / Agricultural Runoff · measured in mg/L
A common nutrient pollutant from fertilizer and waste runoff. It's one of the most frequently detected contaminants in agricultural and rural well water.
Common sources
Fertilizer and manure runoff from farmland, livestock operations, and leaking septic systems, especially after heavy rain.
Health risks
High nitrate levels can cause methemoglobinemia ('blue baby syndrome') in infants under 6 months, which reduces the blood's oxygen-carrying capacity and can be fatal if untreated. Emerging epidemiological research also links long-term elevated nitrate exposure to increased risk of colorectal cancer and thyroid dysfunction.
Sources & further reading
- EPA — Basic Information about Nitrate in Drinking Water
- Ward MH et al. (2018), 'Drinking Water Nitrate and Human Health: An Updated Review', IJERPH, 15(7):1557
- Temkin A et al. (2019), 'Exposure-based assessment ... nitrate in United States drinking water', Environmental Research, 176:108442
How ClearDive rates severity
Readings are bucketed for map color-coding using thresholds referenced from EPA regulatory limits where available. This is a simplified public-awareness scale, not a substitute for certified lab analysis.
How to test for it
Field test strips (colorimetric) give a fast estimate; a nitrate meter or lab analysis is more precise, especially near the regulatory limit.