Twin Lakes Utilities

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: 300 people
Connections: 400
Water source: Groundwater bought from another system
Based in: Rockwell City, IA
County: Calhoun
Owner: Private

The 2 ZIP codes it serves

50563, 50579

The short answer

Nothing in EPA’s and Iowa’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.

What was found

Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 2.3 ppm, for the period ending Dec. 31, 2003. None since is on file, so it is not counted as a current finding.

Total trihalomethanes (TTHM), nitrate and haloacetic acids (HAA5): Iowa’s own results, samples taken from Nov. 2, 2020 to Aug. 11, 2025, with EPA’s 2012 to 2019 file for earlier years.

Fluoride, arsenic and chromium (total): EPA’s compliance monitoring file, samples taken from Nov. 5, 2013 to Nov. 5, 2013. Newer results are in the utility’s annual water quality report.

Below EPA’s limits4

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

27ppb

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 27 ppb, in 2025, 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 7.6 ppb, in 2016.

What handles it

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

Nitrate

Comes from the source

Below EPA’s limits

1.7ppm

One sample

2020, one sample: 1.7 ppm

The highest sample, in 2020, was 1.7 ppm, below EPA’s legal limit of 10 ppm. That is the only year on file, and its one sample was 1.7 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.0 ppm, in 2016.

What handles it

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

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.43ppm

Highest yearly average, 2013

Averaged by year, the highest was 0.43 ppm, in 2013, below EPA’s legal limit of 4.0 ppm. That is the only year on file.

What handles it

NSF/ANSI 58 look for “Fluoride Reduction”
NSF/ANSI 53 look for “Fluoride”

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

6.1ppb

Highest yearly average, 2022 to 2025

2025: not found

Averaged by year, the highest was 6.1 ppb, in 2022, below EPA’s legal limit of 60 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 18.3 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

Arsenic
Chromium (total)
Lead

Violations since 2016

No health-based violations on file with EPA since 2016. There are 2 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

Everything else. Total trihalomethanes (TTHM), nitrate and haloacetic acids (HAA5) results here are Iowa’s own from 2020 on, with EPA’s national file for 2012 to 2019. Fluoride, arsenic and chromium (total) come from EPA’s file alone, which ends in 2019. Twin Lakes Utilities’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; Iowa’s results run from Nov. 2, 2020 to Aug. 11, 2025; EPA’s compliance samples are from Nov. 5, 2013 to Nov. 5, 2013.

Testing your own tap

Twin Lakes Utilities’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 Twin Lakes Utilities serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

AgSource
Ellsworth, IA · about 53 miles
Certified for bacteria, nitrate, metals, minerals and other inorganics
(515) 297-8103
Foundation Analytical Laboratory
Cherokee, IA · about 54 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, PFAS
(712) 225-6989
State Hygienic Laboratory - Lakeside
Milford, IA · about 66 miles
Certified for bacteria, nitrate, minerals and other inorganics
(712) 337-3669

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