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Rainbow Estates

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
30 people
Connections
14
Water source
Groundwater
Based in
Glendive, MT
County
Dawson
Owner
Private

The short answer

1 result is above the limit’s level with no violation recorded, and 1 more is above the health goal. The worst: Fluoride, above the limit’s level, no violation. 3 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2014 to 2024.

Fluoride, total trihalomethanes (TTHM), nitrate, arsenic, chromium (total) and uranium: Montana’s own results, samples taken from Feb. 18, 2021 to Sept. 1, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the limit’s level, no violation recorded1

Fluoride

Forms or is added in treatment

Above the limit’s level, no violation

4.1ppm

Highest yearly average, 2023

Averaged by year, the highest was 4.1 ppm, in 2023, above EPA’s legal limit of 4.0 ppm. Its highest single sample was 5.7 ppm. That is the only year on file. EPA judges this limit on running averages at each sampling point, and recorded no violation for fluoride 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. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.7 ppm, in 2017.

What handles it

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

1.0ppb

90th percentile, 2022 to 2024

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

0.52ppb

Highest yearly average, 2023

Averaged by year, the highest was 0.52 ppb, in 2023, below EPA’s legal limit of 80 ppb. That is the only year on file.

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

0.02ppm

Highest sample; found in 3 of 6

2026: not found

The highest sample, in 2023, was 0.02 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.5 ppm, in 2019.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Uranium

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: Fluoride, Lead Reduction

    For: Fluoride, Lead

  • NSF/ANSI 58

    Claims: Fluoride Reduction, Lead Reduction

    For: Fluoride, 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 fluoride, ranked

The best water filters for lead, ranked

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Revised Total Coliform RuleColiform results required a check of the system, and the check or its fixes were not done on time.EPA: Treatment Technique, Level 1 Assessment (RTCR)June 27, 2026—Unaddressed
Revised Total Coliform RuleColiform or E. coli results required a detailed review of the system, and it or its fixes were not done on time.EPA: Treatment Technique, Level 2 Assessment (RTCR)Nov. 29, 2023—Resolved
Revised Total Coliform RuleColiform results required a check of the system, and the check or its fixes were not done on time.EPA: Treatment Technique, Level 1 Assessment (RTCR)Jan. 18, 2023—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 58 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Fluoride, total trihalomethanes (TTHM), nitrate, arsenic, chromium (total) and uranium results here are Montana’s own from 2021 on, with EPA’s national file for 2012 to 2019. Rainbow Estates’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 Feb. 18, 2021 to Sept. 1, 2026.

Testing your own tap

Rainbow Estates’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 Rainbow Estates 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 MT0004873. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Dawson County

All Montana utilities

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