Nitrates are the most common chemical contaminant in private wells. They are colorless, odorless, and tasteless — impossible to detect without testing. At high levels they are dangerous for infants and concerning for pregnant women.
| Nitrate Level | EPA Status | Risk | Action |
|---|---|---|---|
| 0–5 mg/L | Well below limit | Safe for all ages | No action needed |
| 5–10 mg/L | Approaching limit | Safe for adults; monitor | Retest annually |
| 10 mg/L | EPA Maximum Contaminant Level | Unsafe for infants under 6 months | Treatment required |
| 10–20 mg/L | Above EPA limit | Dangerous for infants, concerning for pregnant women | Treat immediately |
| 20+ mg/L | Significantly elevated | Serious risk for all vulnerable groups | Do not use for drinking or cooking |
Nitrates in the body convert to nitrites, which interfere with hemoglobin's ability to carry oxygen. In infants under 6 months, this causes methemoglobinemia — also called "blue baby syndrome." The infant's skin turns bluish from oxygen deprivation. This condition can be fatal if not treated promptly.
Adults have stomach acid that prevents nitrite formation; infants do not. Adults can safely drink water at 10 mg/L that would be dangerous for an infant.
A point-of-use reverse osmosis system installed under the kitchen sink removes 85–95% of nitrates. This is the most cost-effective solution for most households — it treats the water at the tap where you drink and cook. Cost: $200–$500 for the unit, plus annual filter replacement ($50–$100). Does NOT protect bath water — not a concern for adults but be cautious with infant baths at very high levels.
A whole-house ion exchange system (different from a standard water softener) removes nitrates throughout the home. Cost: $1,000–$3,000 installed. Higher upfront cost but whole-house protection.
Distillation removes nitrates completely but is slow and produces small amounts of water. A countertop distiller costs $150–$400. Best as a temporary solution.
What does NOT remove nitrates: Standard carbon filters, boiling (boiling actually concentrates nitrates), water softeners, and UV systems. Only reverse osmosis, ion exchange, or distillation effectively removes nitrates.
If your nitrate level exceeds 10 mg/L and you have an infant under 6 months, use bottled water for formula and all infant food preparation immediately. Install a reverse osmosis system as soon as possible. Retest the well annually — nitrate levels fluctuate seasonally with rainfall and agricultural cycles.
Nitrates convert to nitrites in the body, which interfere with hemoglobin's ability to carry oxygen. In infants under 6 months, this causes methemoglobinemia ('blue baby syndrome'), which can be fatal if not treated promptly. Adults have stomach acid that prevents this conversion, so they can safely drink water levels that would be dangerous for an infant.
The EPA Maximum Contaminant Level is 10 mg/L, which is already unsafe for infants under 6 months. Levels of 10-20 mg/L are dangerous for infants and concerning for pregnant women; above 20 mg/L is a serious risk for all vulnerable groups and shouldn't be used for drinking or cooking.
Agricultural fertilizer is the leading source in rural areas, leaching through soil into groundwater. Failing or undersized septic systems, livestock manure runoff, and natural organic matter decomposition also contribute.
No — boiling does not remove nitrates and can actually concentrate them as water evaporates, similar to arsenic. Nitrates require reverse osmosis, distillation, or ion exchange treatment to remove.
A point-of-use reverse osmosis system installed under the kitchen sink is the most practical option for treating nitrates in drinking and cooking water.
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