Nitrate in Drinking Water
Nitrate can come from fertilizer, septic systems and manure. EPA's legal limit is 10 mg/L measured as nitrogen. High nitrate is a particular risk for infants under six months, so it is a priority test for private wells near farms or septic systems.
Detection vs violation
- Detection: a lab found a substance. Many substances are detected at levels below the legal limit.
- MCL (legal limit): the highest level EPA allows. Going over it, usually as an average over time, is a violation.
- MCLG: a health goal with no enforcement. It can be zero (for lead it is zero).
- Action level (lead and copper): a trigger for extra steps such as corrosion control and public education. Exceeding it is not a violation by itself.
- Monitoring or reporting violation: a test or report was late or missing. It does not by itself mean a contaminant was too high.