Nitrate in Well Water: Agricultural Runoff & Your Health
2026-03-30 · 6 min read · Contaminant Guide
Agricultural Connection
Nitrate is the most widespread groundwater contaminant in the US, primarily from agricultural fertilizers, animal manure, and septic systems. Areas with intensive row crop farming (corn, soybeans) and concentrated animal feeding operations (CAFOs) have the highest nitrate levels in groundwater.
Health Risks
The EPA MCL for nitrate is 10 mg/L. Above this level, nitrate can cause methemoglobinemia ("blue baby syndrome") in infants under six months. Emerging research links long-term exposure to colorectal cancer, thyroid disease, and neural tube defects.
Most Affected Areas
The Corn Belt states (Iowa, Illinois, Nebraska, Indiana) and California's Central Valley have the highest nitrate contamination rates. Shallow wells in sandy soils near cropland are most vulnerable.
Treatment
Reverse osmosis, ion exchange, and distillation can remove nitrate. Standard carbon filters do NOT remove nitrate. Boiling water concentrates nitrate rather than removing it. Well depth and proper construction are the best prevention measures.
Our team analyzes data from EPA SDWIS & USGS to deliver accurate, up-to-date information. All data is verified and cross-referenced with official sources.