Nitrate in Drinking Water
Inorganic Chemical · MCL: 10 ppm · 1 systems exceeding limit
Overview
Nitrate is one of the most common groundwater contaminants in rural areas. The EPA set the MCL at 10 ppm (mg/L), measured as nitrogen. Agricultural states with intensive farming often see higher nitrate levels in drinking water. Climate change and increased fertilizer use are making nitrate contamination worse in many regions. The EPA Safe Drinking Water program sets and enforces the maximum contaminant levels shown here.
Health Effects
High nitrate levels are especially dangerous for infants under 6 months, causing 'blue baby syndrome' (methemoglobinemia), which reduces the blood's ability to carry oxygen. In adults, long-term exposure may increase cancer risk and thyroid problems. Pregnant women are also at elevated risk.
Sources of Contamination
Nitrate contamination comes primarily from agricultural runoff (fertilizers and animal waste), septic systems, and wastewater treatment plant discharges. Groundwater in agricultural areas is most susceptible. Heavy rainfall can increase nitrate levels by washing fertilizers into water sources.
Treatment & Removal
Ion exchange, reverse osmosis, and electrodialysis can remove nitrate from drinking water. Home reverse osmosis systems are effective at the point of use. Boiling water does NOT remove nitrate and can actually increase its concentration. Distillation also works for home treatment.
How to Remove Nitrate From Water
These filtration methods are effective for reducing Nitrate in drinking water:
| Filter Method | Effectiveness | Cost Range | Certification |
|---|---|---|---|
| Reverse Osmosis (RO) | 85-95% removal | $200-500 (under-sink) | NSF/ANSI 58 |
| Ion Exchange | 90-95% removal | $300-1000 (point-of-use) | NSF/ANSI 53 |
| Distillation | 90%+ removal | $100-400 (countertop) | NSF/ANSI 62 |
Reverse Osmosis (RO), details
Most effective consumer method for nitrate. Critical for infant formula preparation.
Ion Exchange, details
Anion exchange specifically for nitrate. Requires regular regeneration.
Distillation, details
Effective but slow output.
Water Systems with Nitrate Detected
Columbus Public Water System
Columbus, Ohio
City of Baltimore
Baltimore, Maryland
Tucson City Of
Tucson, Arizona
City of Fresno
Fresno, California
Mesa City Of
Mesa, Arizona
Cocoa, City Of
Cocoa, Florida
Glen Burnie-Broadneck
Millersville, Maryland
Gilbert, Town Of
Gilbert, Arizona
Chandler City Of
Chandler, Arizona
Wildwood City Water Department
Rio Grande, New Jersey
Provo City
Provo, Utah
Harford County D.p.w.
Abingdon, Maryland
Carson City Public Works
Carson City, Nevada
Frequently Asked Questions
Nitrate has been detected in 1 water systems that exceed the EPA maximum contaminant level (MCL) of 10 ppm, affecting approximately 1,305,946 people. Check your local water system's annual Consumer Confidence Report or search by ZIP code on this site.
High nitrate levels are especially dangerous for infants under 6 months, causing 'blue baby syndrome' (methemoglobinemia), which reduces the blood's ability to carry oxygen. In adults, long-term exposure may increase cancer risk and thyroid problems. Pregnant women are also at elevated risk.
Effective filtration methods for Nitrate include Reverse Osmosis (RO), Ion Exchange, Distillation. Look for filters certified to NSF/ANSI standards for Nitrate removal. See the detailed comparison table above for effectiveness ratings and cost ranges.
The EPA Maximum Contaminant Level (MCL) for Nitrate is 10 ppm. The MCL Goal (MCLG), the level with no known health risk, is 10 ppm. Water systems must test regularly and notify customers if levels exceed the MCL.