St Paul PWS
What EPA’s and CDC’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
- 1,700 people
- Connections
- 692
- Water source
- Groundwater
- Based in
- O'Fallon, MO
- County
- St. Charles
- Owner
- Local government
The ZIP code it serves
The short answer
Nothing in EPA’s and CDC’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
Total trihalomethanes (TTHM), nitrate, arsenic and haloacetic acids (HAA5): Missouri’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2023, with EPA’s 2012 to 2019 file for earlier years.
Fluoride and chromium (total): EPA’s compliance monitoring file, samples taken from Dec. 12, 2012 to Jan. 24, 2018. Newer results are in the utility’s annual water quality report.
Below EPA’s limits3
Fluoride
Forms or is added in treatment
1.8ppm
Highest yearly average, 2012 to 2018
Averaged by year, the highest was 1.8 ppm, in 2018, below EPA’s legal limit of 4.0 ppm. That was also the latest year on file.
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
5.5ppb
Highest yearly average, 2021
Averaged by year, the highest was 5.5 ppb, in 2021, below EPA’s legal limit of 80 ppb. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 72.9 ppb, in 2012.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Nitrate
Comes from the source
0.04ppm
Highest yearly average, 2020 to 2023
2023 average: 0.04 ppm
Averaged by year, the highest was 0.04 ppm, in 2020, below EPA’s legal limit of 10 ppm. In 2023, the latest year on file, it averaged 0.04 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.06 ppm, in 2012.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Arsenic
- Chromium (total)
- Haloacetic acids (HAA5)
- Lead
Violations since 2016
No health-based violations on file with EPA since 2016. There is 1 monitoring or reporting violation: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Total trihalomethanes (TTHM), nitrate, arsenic and haloacetic acids (HAA5) results here are Missouri’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Fluoride and chromium (total) come from EPA’s file alone, which ends in 2019. St Paul PWS’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; CDC’s yearly averages for Missouri cover 2020 to 2023; EPA’s compliance samples are from Dec. 12, 2012 to Jan. 24, 2018.
Testing your own tap
The 3 labs Missouri certifies closest to the area St Paul PWS serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
R.M. Wester and Associates Inc.
St. Peters, MO · about 7 miles
Certified for bacteria
Eurofins St. Louis Laboratory
Earth City, MO · about 15 miles
Certified for radioactivity
Brothers Lab Services
Maryland Heights, MO · about 17 miles
Certified for nitrate, lead and copper, metals, minerals and other inorganics
Missouri State Public Health Laboratory: Coliform and E. coli testing for private wells and other private drinking water sources, in kits from your local public health agency. A free state courier can carry the sample to the lab overnight. The handling fee is $10, by check or money order. Private Drinking Water Bacteriological Testing, Missouri Department of Health and Senior Services.
All 64 certified labs for MissouriSources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- CDC Environmental Public Health Tracking Network, yearly averages Missouri supplied to CDC, 2020 to 2023, read Oct. 8, 2026. TapBuff’s comparisons with EPA’s limits are its own, not CDC’s or Missouri’s.
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: Missouri DNR, certified microbiological and chemical 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 MO6011535. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Nothing here is above a health goalIn EPA’s and CDC’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 reportSt Paul PWS must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.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