West Mesa Domestic Water Assn
What EPA’s and Washington’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
- 316 people
- Connections
- 114
- Water source
- Groundwater
- Based in
- Othello, WA
- County
- Franklin
- Owner
- Private
- Hardness
- Soft
The short answer
Nothing in EPA’s and Washington’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
Fluoride, total trihalomethanes (TTHM), haloacetic acids (HAA5), arsenic, chromium (total) and nitrate: Washington’s own results, samples taken from Nov. 2, 2020 to Oct. 14, 2025, with EPA’s 2012 to 2019 file for earlier years.
Below EPA’s limits3
Fluoride
Forms or is added in treatment
2.6ppm
Highest yearly average, 2020 to 2025
2025, one sample: 2.5 ppm
Averaged by year, the highest was 2.6 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. In 2025, the latest year on file, its one sample was 2.5 ppm.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Total trihalomethanes (TTHM)
Forms or is added in treatment
20.6ppb
Highest yearly average, 2022 to 2025
2025, one sample: 11.6 ppb
Averaged by year, the highest was 20.6 ppb, in 2022, below EPA’s legal limit of 80 ppb. In 2025, the latest year on file, its one sample was 11.6 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 24.8 ppb, in 2013.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
2.5ppb
Highest yearly average, 2022 to 2025
2025, one sample: 1.7 ppb
Averaged by year, the highest was 2.5 ppb, in 2022, below EPA’s legal limit of 60 ppb. In 2025, the latest year on file, its one sample was 1.7 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.8 ppb, in 2015.
What handles it
No certification claim covers this compound yet.
4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Arsenic
- Chromium (total)
- Lead
- Nitrate
Hardness
Soft, 3.4 mg/L (0.2 grains per gallon), at its one sampling point, in 2020.
Hardness is calcium and magnesium. EPA sets no limit for it: it shows up as scale on fixtures and in water heaters, and as soap that won’t lather. USGS calls water above 60 mg/L moderately hard, above 120 hard and above 180 very hard.
Violations since 2016
No health-based violations on file with EPA since 2016. There are 7 monitoring or reporting violations: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Fluoride, total trihalomethanes (TTHM), haloacetic acids (HAA5), arsenic, chromium (total) and nitrate results here are Washington’s own from 2020 on, with EPA’s national file for 2012 to 2019. West Mesa Domestic Water Assn’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; Washington’s results run from Nov. 2, 2020 to Oct. 14, 2025.
Testing your own tap
No lab Washington certifies is within 75 miles of the area West Mesa Domestic Water Assn serves on the state’s list. Some take samples by mail; the state’s page lists them all.
All 84 certified labs for WashingtonSources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- Washington State Department of Health, Office of Drinking Water, results from Jan. 1, 2020 to Sept. 29, 2026, read Oct. 8, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Hardness: Washington State Department of Health, Office of Drinking Water, results from Nov. 2, 2020 to Nov. 2, 2020, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID WA5394830. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Nothing here is above a health goalIn EPA’s and Washington’s records for this utility. They don’t cover everything, which is why the next step matters.Every contaminant TapBuff tracks
- Get the utility’s own reportWest Mesa Domestic Water Assn 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
- Decide if you want a filter at allA filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.NSF/ANSI standards, decoded