City of Ronan
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
- 2,483 people
- Connections
- 1,011
- Water source
- Surface water
- Based in
- Ronan, MT
- County
- Lake
- Owner
- Local government
The ZIP code it serves
The short answer
2 results are above the health goal. The worst: Uranium, above the health goal. No health-based violations on file since 2016.
What handles itWhat was found
Uranium, arsenic, total trihalomethanes (TTHM), nitrate, fluoride, chromium (total) and haloacetic acids (HAA5): Montana’s own results, samples taken from Aug. 11, 2020 to Aug. 14, 2026, with EPA’s 2012 to 2019 file for earlier years.
Above the health goal2
Uranium
Comes from the source
1.5ppb
Highest yearly average, 2023
Averaged by year, the highest was 1.5 ppb, in 2023: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 1.7 ppb. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.3 ppb, in 2013.
What handles it
- NSF/ANSI 58 look for “Uranium”
Arsenic
Comes from the source
0.5ppb
Highest yearly average, 2020 to 2025
2025: not found
Averaged by year, the highest was 0.5 ppb, in 2021: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 1.0 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 0.67 ppb, in 2013.
What handles it
- NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
- NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
Below EPA’s limits3
Total trihalomethanes (TTHM)
Forms or is added in treatment
3.8ppb
Highest yearly average, 2020 to 2026
2026: not found
Averaged by year, the highest was 3.8 ppb, in 2020, below EPA’s legal limit of 80 ppb. Its highest single sample was 9.2 ppb. 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 yearly average of 8.3 ppb, in 2015.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Nitrate
Comes from the source
0.17ppm
Highest sample; found in 4 of 4
2023, one sample: 0.17 ppm
The highest sample, in 2023, was 0.17 ppm, below EPA’s legal limit of 10 ppm. That was also the latest year on file, and its one sample was 0.17 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.18 ppm, in 2014.
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
0.04ppm
Highest yearly average, 2020 to 2023
Averaged by year, the highest was 0.04 ppm, in 2023, below EPA’s legal limit of 4.0 ppm. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.05 ppm, in 2016.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Chromium (total)
- Haloacetic acids (HAA5)
- 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: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claims: Uranium, Arsenic (Pentavalent)<=50 ppb Reduction
For: Uranium, Arsenic
Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)
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
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Arsenic
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Violations since 2016
No health-based violations on file with EPA since 2016. There are 24 monitoring or reporting violations: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Uranium, arsenic, total trihalomethanes (TTHM), nitrate, fluoride, chromium (total) and haloacetic acids (HAA5) results here are Montana’s own from 2020 on, with EPA’s national file for 2012 to 2019. City of Ronan’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. 11, 2020 to Aug. 14, 2026.
Testing your own tap
The 3 labs Montana certifies closest to the area City of Ronan serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Mission Mountain Laboratories
Ravalli, MT · about 16 miles
Certified for bacteria
Missoula CCHD Water Lab
Missoula, MT · about 44 miles
Certified for bacteria
RD Water Lab, LLC
Missoula, MT · about 45 miles
Certified for bacteria
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 MontanaSources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- Montana Department of Environmental Quality, Public Water Supply, results from Jan. 2, 2020 to Oct. 6, 2026, read Oct. 18, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: Montana Department of Public Health and Human Services, Water Laboratory Certification Program, certified laboratories, read Oct. 10, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID MT0000318. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 2 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Uranium
- Get the utility’s own reportCity of Ronan must send you a water quality report every year. It covers contaminants this page does not show.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs