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Nitrate in drinking water

Also called Nitrate (as N), Nitrate-nitrogen, NO3.

Legal limit
10 ppm
Health goal
10 ppm

Values in parts per million (ppm). Comes from the source.

Where the rules stand

Final MCL and health goal of 10 ppm, measured as nitrogen (10 mg/L as N). Nitrite has its own MCL of 1 ppm as nitrogen.

The scale every TapBuff report uses for this contaminant: the legal line at the middle, twice it at the right.

What EPA says about health

EPA says infants under six months who drink water with nitrate above the MCL could become seriously ill. Symptoms include shortness of breath and blue-baby syndrome.

Where it comes from

EPA lists fertilizer runoff, leaking septic tanks and sewage, and erosion of natural deposits.

What handles it

  • NSF/ANSI 58

    Claim to look for: Nitrate/Nitrite Reduction

    NSF listing wording. WQA lists "Nitrate" and "Nitrite" as separate claims. NSF lists no nitrate claim under 53.

Filters with that claim on a certifier’s listing

Sources

  1. National Primary Drinking Water Regulations, U.S. EPA. Checked Oct. 4, 2026.
  2. Search for NSF Certified Drinking Water Treatment Units (standards and reduction claims lists), NSF. Checked Oct. 4, 2026.
  3. Contaminant Reduction Claims Guide, NSF. Checked Oct. 4, 2026.
  4. Find WQA Certified Products (Gold Seal listings by standard and claim), Water Quality Association. Checked Oct. 4, 2026.
  5. SDWA Dataset Download Summary (codes from SDWA_REF_CODE_VALUES.csv, 2026 Q2 extract), U.S. EPA ECHO. Checked Oct. 4, 2026.