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Mendon Water Department

What EPA’s and Massachusetts’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
470 people
Connections
153
Water source
Groundwater bought from another system
Based in
Mendon, MA
County
Worcester
Owner
Local government
The ZIP code it serves

01756

The short answer

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

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2002 to 2025.

Total trihalomethanes (TTHM) and haloacetic acids (HAA5): Massachusetts’s own results, samples taken from Aug. 17, 2020 to Aug. 26, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

1.0ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 1.0 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

Below EPA’s limits2

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

74ppb

Highest yearly average, 2020 to 2026

2026 average: 38 ppb

Averaged by year, the highest was 74 ppb, in 2020, below EPA’s legal limit of 80 ppb. Its highest single sample was 81 ppb. In 2026, the latest year on file, its three samples averaged 38 ppb. EPA recorded no violation for total trihalomethanes (TTHM) at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 79 ppb, in 2019.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

30ppb

Highest yearly average, 2020 to 2026

2026 average: 22.1 ppb

Averaged by year, the highest was 30 ppb, in 2020, below EPA’s legal limit of 60 ppb. Its highest single sample was 40 ppb. In 2026, the latest year on file, its three samples averaged 22.1 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 32 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

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.”

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. 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

The best water filters for lead, ranked

Violations since 2016

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

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM) and haloacetic acids (HAA5) results here are Massachusetts’s own from 2020 on, with EPA’s national file for 2012 to 2019. Mendon Water Department’s own annual report, which it must send you every year, has 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; Massachusetts’s results run from Aug. 17, 2020 to Aug. 26, 2026.

Testing your own tap

Mendon Water Department’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 Massachusetts certifies.

The 3 labs Massachusetts certifies closest to the area Mendon Water Department serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Proverde Environmental, Inc.

    Milford, MA · about 5 miles

    Certified for PFAS

    (617) 221-3356

  • Pace Analytical LLC-Westborough

    Westborough, MA · about 13 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (508) 898-9220

  • Pace Analytical LLC-Mansfield-320 Forbes

    Mansfield, MA · about 18 miles

    Certified for lead and copper, metals, PFAS

    (508) 822-9300

All 81 certified labs for Massachusetts

Sources

PWSID MA2179000. Rebuilt from EPA data on Oct. 18, 2026.

Also in Worcester County

All Massachusetts utilities

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