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Casitas del Rio

What EPA’s and Montana’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
216 people
Connections
124
Water source
Surface water bought from another system
Based in
Glendive, MT
County
Dawson
Owner
Private
The ZIP code it serves

59330

The short answer

1 result is above the limit’s level with no violation recorded. The worst: Total trihalomethanes (TTHM), above the limit’s level, no violation. No health-based violations on file since 2016.

What handles it

What was found

Total trihalomethanes (TTHM) and haloacetic acids (HAA5): Montana’s own results, samples taken from Aug. 25, 2021 to Sept. 1, 2026.

Above the limit’s level, no violation recorded1

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the limit’s level, no violation

98ppb

Highest yearly average, 2021 to 2026

2026 average: 39 ppb

Averaged by year, the highest was 98 ppb, in 2021, above EPA’s legal limit of 80 ppb. In 2026, the latest year on file, its two samples averaged 39 ppb. EPA judges this limit on running averages at each sampling point, and recorded no violation for total trihalomethanes (TTHM) at this utility since 2020. Results like these with no violation often include water sampled before treatment or blending; the utility’s annual report says what reaches the tap.

What handles it

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

Below EPA’s limits1

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

53ppb

Highest yearly average, 2021 to 2026

2026 average: 18 ppb

Averaged by year, the highest was 53 ppb, in 2021, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, its two samples averaged 18 ppb.

What handles it

No certification claim covers this compound yet.

One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • 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: Trihalomethanes (TTHM) Reduction

    For: Total trihalomethanes (TTHM)

    Other certifiers’ wording: VOC Reduction

  • NSF/ANSI 58

    Claim: Trihalomethanes (TTHM) Reduction

    For: Total trihalomethanes (TTHM)

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

Violations since 2016

No health-based violations on file with EPA since 2016. There are 74 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM) and haloacetic acids (HAA5) results here are Montana’s own from 2021 on, with EPA’s national file for 2012 to 2019. Casitas del Rio’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; Montana’s results run from Aug. 25, 2021 to Sept. 1, 2026.

Testing your own tap

Casitas del Rio’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 Montana certifies.

No lab Montana certifies is within 75 miles of the area Casitas del Rio serves on the state’s list. Some take samples by mail; the state’s page lists them all.

Montana State Environmental Laboratory: Private well testing packages for bacteria, metals, nutrients, anions, organic chemicals and more, open to the public. Samples can be mailed, sent by the lab's free courier, or dropped off at the lab. Environmental Laboratory, Montana Department of Public Health and Human Services.

All 36 certified labs for Montana

Sources

PWSID MT0005060. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Dawson County

All Montana utilities

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