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Mahnomen

What EPA’s and Minnesota’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves
1,217 people
Connections
546
Water source
Groundwater
Based in
Mahnomen, MN
County
Mahnomen
Owner
Local government
The ZIP code it serves

56557

The short answer

1 result is above the health goal. The worst: Arsenic, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Arsenic and nitrate: Minnesota’s yearly summaries per water system, 2023 to 2025, with EPA’s 2012 to 2019 file for earlier years.

Fluoride and chromium (total): EPA’s compliance monitoring file, samples taken from Jan. 30, 2012 to Oct. 23, 2019. Newer results are in the utility’s annual water quality report.

Above the health goal1

Arsenic

Comes from the source

Above the health goal

4.4ppb

Highest yearly average, 2023 to 2025

Averaged by year, the highest was 4.4 ppb, in 2025: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.8 ppb, in 2019.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”

Below EPA’s limits2

Fluoride

Forms or is added in treatment

Below EPA’s limits

1.3ppm

Highest yearly average, 2012 to 2019

2019 average: 0.85 ppm

Averaged by year, the highest was 1.3 ppm, in 2012, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 1.3 ppm. In 2019, the latest year on file, its four samples averaged 0.85 ppm.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

0.6ppm

Highest yearly average, 2023 to 2025

Averaged by year, the highest was 0.6 ppm, in 2025, below EPA’s legal limit of 10 ppm. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.59 ppm, in 2014.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
2 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)
  • Lead

What handles it

A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”

  • NSF/ANSI 53

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

    Other certifiers’ wording: Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

    Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)

At the tap, or for the whole house?

These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.

Filters with those claims on a certifier’s listing

Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

Compare five-year costs

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Violations since 2016

No health-based violations on file with EPA since 2016.

What this report can’t tell you

  • Everything else. Arsenic and nitrate results here are Minnesota’s own yearly summaries from 2023 on, with EPA’s national file for 2012 to 2019. Fluoride and chromium (total) come from EPA’s file alone, which ends in 2019. Mahnomen’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.

  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.

  • What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.

  • Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; Minnesota’s yearly summaries cover 2023 to 2025; EPA’s compliance samples are from Jan. 30, 2012 to Oct. 23, 2019.

Testing your own tap

Mahnomen’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Minnesota certifies.

The 2 labs Minnesota certifies closest to the area Mahnomen serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • RMB Environmental Laboratories, Inc. – Detroit Lakes

    Detroit Lakes, MN · about 33 miles

    Certified for bacteria, nitrate, lead and copper, metals

    (218) 846-1465

  • AC Analytical & Consulting, LLC

    Puposky, MN · about 50 miles

    Certified for bacteria, nitrate

    (218) 243-3328

All 24 certified labs for Minnesota

Sources

PWSID MN1440002. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Nearby

All Minnesota utilities

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