Nitrates in Well Water: Health Risks, Limits and Fixes

On this page

1. Where nitrate comes from
2. The limit: 10 mg/L as nitrogen
3. Why infants are most at risk
4. When to test
5. Boiling makes it worse
6. Treatment options
7. FAQ
8. Sources

Where nitrate comes from

According to CDC, nitrate can come from animal waste, septic systems, wastewater, flooded sewers, polluted stormwater, fertilizers, farm runoff and decaying plants, depending on the geology around your well. EPA lists fertilizer runoff, leaking septic tanks and sewage, and erosion of natural deposits as the main sources (EPA).

The limit: 10 mg/L as nitrogen

EPA’s maximum contaminant level for nitrate is 10 mg/L measured as nitrogen. For nitrite it’s 1 mg/L (EPA). These are standards for public water, but they’re the standard reference for private wells too.

Watch the units. Some labs report “nitrate-nitrogen” and others report “nitrate.” Penn State Extension explains that 10 mg/L nitrate-nitrogen equals 45 mg/L nitrate. A result of “30 mg/L nitrate” is under the limit; “30 mg/L nitrate-N” is three times over it. If your report doesn’t say which, ask the lab.

Why infants are most at risk

EPA’s health-effects statement: infants under six months who drink water with nitrate above the limit “could become seriously ill and, if untreated, may die,” with symptoms including shortness of breath and blue-baby syndrome (EPA). Formula mixed with well water is the main exposure route (Penn State Extension). CDC adds that high nitrate levels can make “you, and especially babies, sick” (CDC).

If your result is high and there’s an infant or pregnant person in the home, use another safe water source for drinking and formula while you talk to your health care provider and health department.

When to test

• Every year, for every well owner (CDC).
• Early in pregnancy, before bringing a baby home, and during the baby’s first six months (EPA fact sheet).
• Spring or summer after a rainy period, when EPA says levels are best measured.
• If you’re near intensive agriculture, test for nitrate, nitrite, pesticides and coliform (EPA).

CDC also notes that high nitrate can be a sign of other contamination, so ask your health department whether to test for anything else.

Boiling makes it worse

Boiling doesn’t remove nitrate. As Penn State Extension puts it, it “increases nitrate concentrations as water evaporates.”

Treatment options

According to Penn State Extension, ion exchange, reverse osmosis and distillation all remove nitrate from drinking water. All three are usually installed to treat drinking and cooking water rather than the whole house.

Minnesota’s health department also lists RO and distillation as reducing nitrate and nitrite (MDH treatment table).

Buy certified. Choose a unit with a certified nitrate/nitrite reduction claim, such as an NSF/ANSI 58 RO system, and confirm it in NSF’s listings. Then retest the treated water to make sure it works.

RO options to compare (check each model’s certification listing for nitrate first): SpringWell: reverse osmosis systems → · iSpring: RO systems → · APEC Water: RO systems → · Aquasana: RO systems →

Also consider the source. Penn State notes nitrate is costly to treat. Before buying equipment, ask your health department or a licensed well contractor whether well location, construction or a nearby septic system is part of the problem.

Monitoring between lab tests: nitrate test strips WaterTestingKits.com: nitrate test strips → can flag changes, but confirm any concern with a certified lab.

FAQ

Will a water softener or carbon filter remove nitrate? They aren’t on the lists of nitrate treatments from Penn State or the Minnesota Department of Health. Use a treatment certified for nitrate.

Can I shower in water with high nitrate? EPA’s health statement is about drinking the water. Ask your health department about your specific result.