Safe nitrate levels in well water
Short answer: The EPA's legal limit for public drinking water is 10 milligrams per liter of nitrate measured as nitrogen. The EPA warns that infants under six months who drink water above that level could become seriously ill, with symptoms including shortness of breath and blue-baby syndrome. The CDC says all well owners should test for nitrates every year.
The number to know
The EPA's maximum contaminant level (MCL) for nitrate, measured as nitrogen, is 10 mg/L. Infants below six months who drink water above the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. EPA lists sources as fertilizer runoff, leaking septic tanks and sewage, and erosion of natural deposits. [source]
Where nitrate in wells comes from
The CDC lists animal waste, septic systems, wastewater, flooded sewers, polluted stormwater runoff, fertilizers, farm runoff and decaying plants. High nitrate can mean other harmful chemicals or germs are present, so ask your health department what else to test for. [source]
How often to test
The CDC says all well owners should test for nitrates at least once a year [source], and the EPA recommends testing for nitrate, nitrite, pesticides and coliform near intensive agriculture. [source] In Pennsylvania, Penn State's Agriculture/Septic package adds nitrate-nitrogen to the standard test for $70. [source]
If your result is high
The CDC says not to drink water contaminated with chemicals until it's treated, and notes that boiling won't remove chemicals. [source]
FAQ
What is a safe nitrate level in well water?
The EPA's legal limit for public drinking water is 10 milligrams per liter of nitrate measured as nitrogen. The EPA warns that infants under six months who drink water above that level could become seriously ill, with symptoms including shortness of breath and blue-baby syndrome. The CDC says all well owners should test for nitrates every year.
Does boiling well water remove nitrate?
No. The CDC says boiling will not remove chemicals from water.
Who is most at risk from nitrate in water?
The EPA says infants below the age of six months who drink water above the nitrate limit could become seriously ill.
Sources
- US EPA – National Primary Drinking Water Regulations (accessed 2026-10-23)
- CDC – Guidelines for Testing Well Water (accessed 2026-10-23)
- CDC – Guidelines for Treating Well Water (accessed 2026-10-23)
- US EPA – Protect Your Home's Water (accessed 2026-10-23)
- Penn State AASL – Drinking Water Testing (fees) (accessed 2026-10-23)
Informational only, not health, medical, legal or real-estate advice. Programs and fees change; confirm with the official source. See our disclaimer and affiliate disclosure.