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Lewis 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
357 people
Connections
200
Water source
Groundwater
Based in
Lewis, IA
County
Cass
Owner
Local government
The ZIP code it serves

51544

The short answer

1 result is above EPA’s legal limit, and 1 more is above the health goal. The worst: Nitrate, above the legal limit. 1 health-based violation since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2004 to 2025.

Nitrate, fluoride, total trihalomethanes (TTHM), arsenic, chromium (total) and haloacetic acids (HAA5): Iowa’s own results, samples taken from Jan. 20, 2020 to Sept. 9, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit1

Nitrate

Comes from the source

Above the legal limit

14ppm

Highest sample; found in 80 of 80

2026 average: 2.7 ppm

One sample, in 2025, was above EPA’s legal limit of 10 ppm, at 14 ppm. The next sample at the same point, within 30 days, brought the average back under the limit. In 2026, the latest year on file, its nine samples averaged 2.7 ppm. EPA recorded a violation for nitrate at this utility in 2025. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 6.2 ppm, in 2012.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

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 limits2

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.32ppm

Highest yearly average, 2025

Averaged by year, the highest was 0.32 ppm, in 2025, below EPA’s legal limit of 4.0 ppm. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.4 ppm, in 2016.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

5.0ppb

Highest yearly average, 2022 to 2025

2025: not found

Averaged by year, the highest was 5.0 ppb, in 2022, below EPA’s legal limit of 80 ppb. In 2025, 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 5.4 ppb, in 2016.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Haloacetic acids (HAA5)

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

    Claims: Nitrate/Nitrite (30 ppm challenge), Lead Reduction

    For: Nitrate, Lead

  • NSF/ANSI 58

    Claims: Nitrate/Nitrite Reduction, Lead Reduction

    For: Nitrate, Lead

    Other certifiers’ wording: Nitrate

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 reverse osmosis systems, ranked

The best water filters for lead, ranked

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleMarch 1, 2025 to March 31, 202514 MG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 1 monitoring or reporting violation not shown.

What this report can’t tell you

  • Everything else. Nitrate, fluoride, total trihalomethanes (TTHM), arsenic, chromium (total) and haloacetic acids (HAA5) results here are Iowa’s own from 2020 on, with EPA’s national file for 2012 to 2019. Lewis 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 Jan. 20, 2020 to Sept. 9, 2026.

Testing your own tap

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

  • Midwest Laboratories

    Omaha, NE · about 52 miles

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

    (402) 334-7770

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 IA1535078. Rebuilt from EPA data on Oct. 18, 2026.

Also in Cass County

All Iowa utilities

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