Quick answer: The drinking water limit for nitrate is 10 mg/L measured as nitrate-nitrogen (the same as 45 mg/L as nitrate). Above that level, the water should not be used for infants or baby formula. Boiling does not help; it makes nitrate more concentrated. The most common home treatment is a reverse osmosis system at the kitchen sink, and bottled water is a cheap, effective stopgap.
Read your lab report carefully: two units
Labs report nitrate in one of two ways, and mixing them up is a common mistake:
| Reported as | Limit |
|---|---|
| Nitrate-nitrogen (NO₃-N) | 10 mg/L |
| Nitrate (NO₃) | 45 mg/L |
These are the same limit expressed differently. Check which unit your lab used before deciding whether you are over. (1 mg/L = 1 ppm.)
Who is at risk?
According to Penn State Extension:
- Infants, especially under 6 months, are most at risk. When high-nitrate water is used to mix formula, nitrate is converted to nitrite in the baby’s stomach. Nitrite reduces the blood’s ability to carry oxygen, a condition sometimes called “blue baby syndrome.” A key sign is bluish skin, especially around the eyes and mouth. Seek medical care immediately if you notice it.
- Pregnant women should also avoid high-nitrate water; effects such as low birth weight have been reported.
- Healthy adults are generally not considered at significant risk at these levels.
Where nitrate comes from
- Farm fertilizers and manure
- Septic systems
- Lawn and garden fertilizer
- Low natural levels in groundwater
Shallow wells, wells in sandy soil, and wells near crop fields, feedlots or septic drain fields are more likely to have elevated nitrate. High nitrate can also be a sign that other surface contaminants are reaching the well, so it is worth testing for coliform bacteria at the same time.
Why boiling makes it worse
Boiling kills bacteria but does not remove nitrate. As water evaporates, the nitrate that remains becomes more concentrated. Never boil high-nitrate water to make it safe for a baby.
Treatment options
Penn State Extension compares the three main methods:
| Method | How it works | Pros | Cons |
|---|---|---|---|
| Reverse osmosis (RO) | A membrane blocks nitrate | Common under-sink option; also removes many other contaminants | Removes about 83–92% of nitrate, so very high levels may still be above the limit; slow; wastes water |
| Ion exchange | A resin swaps nitrate for chloride | Can treat the whole house | Expensive; needs maintenance; resin prefers sulfate, which can reduce nitrate removal |
| Distillation | Water is boiled and the steam condensed | Very thorough | Very slow (about 1 gallon every 4–5 hours) and uses a lot of energy |
The low-cost option: buy bottled water for infants and pregnant household members. It is an effective and inexpensive solution while you decide on treatment.
Because RO removes a percentage, not all, of the nitrate, test the treated water after installing any system. See our guide to reverse osmosis for well water for what else RO does and doesn’t remove.
Reducing nitrate at the source
- Keep fertilizer, manure and animal pens well away from the wellhead.
- Maintain and pump your septic system on schedule.
- Make sure the well cap is sealed and the casing extends above the ground.
- Retest once a year; nitrate can change with the seasons and nearby land use.
Frequently asked questions
What is a safe nitrate level in well water?
Below 10 mg/L nitrate-nitrogen (45 mg/L nitrate). It is also worth watching the trend: rising levels year over year are a warning sign, even under the limit.
Can I shower in water with high nitrate?
Nitrate is a concern when swallowed, not through the skin, so bathing and showering are generally not considered a risk.
Will a water softener remove nitrate?
A standard softener is not designed for nitrate. Specialized nitrate-selective ion exchange systems exist, but they are different equipment.
Can animals drink high-nitrate water?
Livestock have their own guidelines. Ask your local extension office.
Related guides
- Well water testing: what to test for and how often
- Reverse osmosis for well water
- Coliform bacteria in well water
Sources
This guide is for general information. If an infant has been drinking high-nitrate water and shows signs such as bluish skin, seek medical care immediately.
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