Nitrate
A compound found naturally in soil and water, but elevated levels usually indicate contamination from fertilizers or sewage.
Source
Agricultural runoff, fertilizers, septic systems, and animal feedlots.
Health Risk
Dangerous for infants — can cause "blue baby syndrome" (methemoglobinemia), which interferes with oxygen transport in the blood.
Filter Tip
Reverse osmosis, ion exchange, or distillation can reduce nitrate levels. Standard carbon filters are NOT effective.
Nitrate is one of the most common groundwater contaminants in the United States. While it occurs naturally in small amounts, elevated levels in drinking water are usually caused by agricultural runoff, fertilizers, and septic system leachate.
The EPA's Maximum Contaminant Level for nitrate is 10 parts per million (ppm) measured as nitrogen. This limit was set specifically to protect infants from methemoglobinemia ("blue baby syndrome").
Why Is Nitrate Dangerous?
Nitrate's primary health risk is to infants under 6 months of age:
- Blue Baby Syndrome: Nitrate interferes with the blood's ability to carry oxygen, causing the infant's skin to turn blue. Can be fatal if untreated.
- Pregnant women are also at risk — nitrate may affect fetal development
- Some research links long-term nitrate exposure to colorectal cancer in adults
- Thyroid effects at chronic low-level exposure
Sources of Nitrate in Water
Nitrate in water comes primarily from agricultural fertilizer runoff, animal feeding operations, septic systems, and wastewater treatment plant discharge. Rural areas with intensive farming are most affected.
How to Remove Nitrate From Your Water
- Reverse Osmosis: Removes 83-92% of nitrate — the most accessible home solution
- Ion Exchange: Very effective, designed specifically for nitrate removal
- Distillation: Effective but slow
Important: Standard activated carbon filters (Brita, PUR, etc.) do NOT remove nitrate. Boiling water actually concentrates nitrate.
Nitrate Levels in US Cities
Based on verified municipal water quality reports (Consumer Confidence Reports) from 9 cities.
Detected Within Limits (9)
Frequently Asked Questions
Can adults drink water with high nitrate?
Adults are less sensitive to nitrate than infants, but long-term exposure above 10 ppm may increase cancer risk. Pregnant women should be especially cautious. The EPA limit of 10 ppm is set to protect the most vulnerable.
Does boiling water remove nitrate?
No. Boiling water concentrates nitrate as water evaporates, making it worse. Do not boil water to treat nitrate contamination. Use reverse osmosis or ion exchange instead.
Which areas have high nitrate in water?
Nitrate is most common in agricultural regions, including the Midwest (Iowa, Illinois, Nebraska), California's Central Valley, and areas with intensive livestock operations. Private wells are at higher risk than public water systems.
Related Contaminants
Fluoride
A mineral added to most US water systems to prevent tooth decay. Also occurs naturally in some groundwater.
Arsenic
A naturally occurring element found in rock and soil that can dissolve into groundwater.
Lead
A toxic heavy metal that typically enters drinking water through corroding pipes, faucets, and solder — not from the water source itself.