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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Real EPA measurements of nitrates for Colorado water systems — Six-Year Review compliance samples 2012–2019 (historical). Methodology
These cities have nitrates levels above 50% of the EPA limit but within compliance
| City | Level | % of Limit | Population |
|---|---|---|---|
| Commerce City | 5.34 mg/L | 53.4% | 75,559 |
Every Colorado system with a nitrates result in EPA's data, sorted by level. Averages of 2012–2019 finished-water samples, non-detects counted as zero — historical, not today's tap.
| City | Level | Period | EPA Limit | % of Limit | Status |
|---|---|---|---|---|---|
| Commerce CityGrade A | 5.34 mg/LAverage of 318 samples | 2012–2019 | 10.00 mg/L | 53.4% | Warning |
| BrightonGrade D | 4.41 mg/LAverage of 38 samples | 2012–2019 | 10.00 mg/L | 44.1% | Safe |
| EnglewoodGrade C | 2.19 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 21.9% | Safe |
| FountainGrade A | 1.85 mg/LAverage of 24 samples | 2012–2019 | 10.00 mg/L | 18.5% | Safe |
| VailGrade A | 0.326 mg/LAverage of 48 samples | 2012–2019 | 10.00 mg/L | 3.3% | Safe |
| AuroraGrade A | 0.300 mg/LAverage of 47 samples | 2012–2019 | 10.00 mg/L | 3.0% | Safe |
| ThorntonGrade D | 0.269 mg/LAverage of 11 samples | 2012–2019 | 10.00 mg/L | 2.7% | Safe |
| PuebloGrade A | 0.258 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 2.6% | Safe |
| GoldenGrade A | 0.238 mg/LAverage of 9 samples | 2012–2019 | 10.00 mg/L | 2.4% | Safe |
| LakewoodGrade A | 0.199 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 2.0% | Safe |
| Castle RockGrade B | 0.111 mg/LAverage of 49 samples | 2012–2019 | 10.00 mg/L | 1.1% | Safe |
| ParkerGrade C | 0.106 mg/LAverage of 134 samples | 2012–2019 | 10.00 mg/L | 1.1% | Safe |
| Grand JunctionGrade A | 0.089 mg/LAverage of 20 samples | 2012–2019 | 10.00 mg/L | 0.9% | Safe |
| Colorado SpringsGrade A | 0.079 mg/LAverage of 39 samples | 2012–2019 | 10.00 mg/L | 0.8% | Safe |
| WestminsterGrade A | 0.080 mg/LAverage of 16 samples | 2012–2019 | 10.00 mg/L | 0.8% | Safe |
| DenverGrade A | 0.068 mg/LAverage of 107 samples | 2012–2019 | 10.00 mg/L | 0.7% | Safe |
| Fort CollinsGrade A | 0.065 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 0.7% | Safe |
| ErieGrade A | 0.060 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 0.6% | Safe |
| ArvadaGrade A | 0.032 mg/LAverage of 39 samples | 2012–2019 | 10.00 mg/L | 0.3% | Safe |
| BroomfieldGrade B | 0.028 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 0.3% | Safe |
| LongmontGrade A | 0.030 mg/LAverage of 8 samples | 2012–2019 | 10.00 mg/L | 0.3% | Safe |
| LovelandGrade A | 0.020 mg/LAverage of 5 samples | 2012–2019 | 10.00 mg/L | 0.2% | Safe |
| BoulderGrade A | 0.0083 mg/LAverage of 18 samples | 2012–2019 | 10.00 mg/L | 0.1% | Safe |
| GreeleyGrade A | 0.0096 mg/LAverage of 16 samples | 2012–2019 | 10.00 mg/L | 0.1% | Safe |
| LafayetteGrade A | 0.0069 mg/LAverage of 7 samples | 2012–2019 | 10.00 mg/L | 0.1% | Safe |
Showing 25 of 27 cities. View individual city pages for detailed reports.
Nitrates pose the greatest risk to infants under six months of age. High nitrate levels can cause methemoglobinemia, also known as "blue baby syndrome," which reduces the blood's oxygen-carrying capacity. Pregnant women are also at risk as nitrate exposure has been linked to neural tube defects, preterm birth, and low birth weight. IMPORTANT: Boiling water does NOT remove nitrates - it concentrates them.
Runoff from fertilizer use; leaching from septic tanks; erosion of natural deposits; agricultural runoff
Based on our analysis of EPA Safe Drinking Water Information System (SDWIS) data and local water utility reports,nitrates has been detected in 27 Colorado water systems. The average level across all tested cities is 6% of the EPA Maximum Contaminant Level (MCL), with the highest detection at 53.4% of the limit.
The EPA MCL for nitrate is 10 mg/L measured as nitrogen. The EPA MCL for nitrates is 10 mg/L. This limit is set to protect public health based on available scientific evidence about the contaminant's health effects.
27 Colorado cities have nitrates detected in their water supply. All tested cities are within EPA safety limits.
Blue baby syndrome in infants, pregnancy complications, potential cancer risk. The most vulnerable groups include infants under 6 months and pregnant women.
The most effective methods for removing nitrates include Reverse Osmosis, Ion Exchange, Distillation. Look for filters certified by NSF/ANSI for nitrates reduction.
The EPA Maximum Contaminant Level (MCL) for nitrates is 10 mg/L.The EPA MCL for nitrate is 10 mg/L measured as nitrogen.
This page shows what Colorado utilities reported for nitrates. It cannot tell you what is coming out of your own tap: utility samples are taken across a whole system and averaged, levels vary by address and season, and anything picked up after the water leaves the main never appears in their report.
Home water test kitscheck your own tap before buying any filterRecommended filtration methods for nitrates removal:
Removes 83-92% of nitrates
Specifically designed for nitrate removal
Effective but energy-intensive
Paid links. We earn a commission if you buy, at no extra cost to you. Filters are matched to the removal methods listed above for nitrates.