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Plymouth Water Supply

What EPA’s and Iowa’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
378 people
Connections
175
Water source
Groundwater
Based in
Plymouth, IA
County
Cerro Gordo
Owner
Local government
The ZIP code it serves

50464

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 2012 to 2025.

Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 1.5 ppm, for the period ending Dec. 31, 2012. None since is on file, so it is not counted as a current finding.

Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, arsenic, chromium (total) and nitrate: Iowa’s own results, samples taken from Feb. 5, 2020 to Aug. 19, 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

2.0ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 2.0 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 limits3

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

11ppb

Highest yearly average, 2022 to 2026

Averaged by year, the highest was 11 ppb, in 2026, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.7 ppb, in 2016.

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

8.0ppb

Highest yearly average, 2022 to 2026

Averaged by year, the highest was 8.0 ppb, in 2026, below EPA’s legal limit of 60 ppb. That was also the latest year on file.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.46ppm

Highest yearly average, 2021 to 2022

2022: not found

Averaged by year, the highest was 0.46 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. In 2022, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.0 ppm, in 2012.

What handles it

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Nitrate

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. There are 39 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, arsenic, chromium (total) and nitrate results here are Iowa’s own from 2020 on, with EPA’s national file for 2012 to 2019. Plymouth Water Supply’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; Iowa’s results run from Feb. 5, 2020 to Aug. 19, 2026.

Testing your own tap

Plymouth Water Supply’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 Iowa certifies.

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

  • Eurofins - Cedar Falls

    Cedar Falls, IA · about 58 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (319) 277-2401

  • AgSource

    Ellsworth, IA · about 68 miles

    Certified for bacteria, nitrate, metals, minerals and other inorganics

    (515) 297-8103

  • Microbac Laboratories - Waterloo

    Waterloo, IA · about 69 miles

    Certified for bacteria, nitrate

    (319) 235-4440

State Hygienic Laboratory at the University of Iowa: Through the Grants-to-Counties program, private well owners in participating counties can have their water tested for total coliform bacteria and nitrate. Start with the county sanitarian at your county health department. No cost in a participating county. The Grants-to-Counties Program, State Hygienic Lab at the University of Iowa.

All 36 certified labs for Iowa

Sources

PWSID IA1759048. Rebuilt from EPA data on Oct. 18, 2026.

Also in Cerro Gordo County

All Iowa utilities

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