Public Water Supply District 2 of St. Charles County (PWSD 2)
8.3 to 10.8 grains per gallon
142 to 184 mg/L. Hard to very hard.
Range across the district's sources.
Serves about 100,000 people. It also sells water to Wentzville and O'Fallon.
Water hardness in Dardenne Prairie, Missouri
Dardenne Prairie water hardness depends on your address. PWSD 2 water runs 8.3 to 10.8 grains per gallon in its 2025 water quality report. Missouri American Water works out to about 5 to 7 grains per gallon from the minerals in its report.
Who supplies water in Dardenne Prairie
Dardenne Prairie homes get PWSD 2 or Missouri American Water, depending on the address. The city's utilities page says so.
Missouri American Water (St. Louis and St. Charles counties)
about 5 to 7 grains per gallon
about 83 to 119 mg/L. Moderately hard.
Our calculation. The report prints no hardness number, so we worked it out from the calcium and magnesium it lists.
Serves parts of O'Fallon and Dardenne Prairie.
Most city water in St. Charles County is hard or very hard
Hardness in grains per gallon, from each utility's 2025 water quality report
- Soft, 0 to 3.5
- Moderately hard, 3.5 to 7
- Hard, 7 to 10.5
- Very hard, over 10.5
- Wentzville (city wells)17.3 gpg
- O'Fallon (city system)7.2 to 16.5 gpg
- PWSD 28.3 to 10.8 gpg
- St. Peters10.1 gpg
- St. Charles (city)8.9 gpg
- Missouri American Waterabout 5 to 7 gpg calculated
Sources: PWSD 2 2025 water quality report and Missouri American Water 2025 water quality report.
What that means at home
At this hardness, scale builds up in water heaters and on fixtures, and soap does not lather well. None of that is a health risk. It is wear on the house and more cleaning.
What we would look at
A test at your tap comes first. It tells us your real hardness and whether your water carries chlorine or chloramine. From there, the usual options are a water softener for scale, a carbon filter for taste and smell, and reverse osmosis for drinking water. Sometimes the answer is none of them.
Common questions
How hard is the water in Dardenne Prairie?
Dardenne Prairie water hardness depends on your address. PWSD 2 water runs 8.3 to 10.8 grains per gallon in its 2025 water quality report. Missouri American Water works out to about 5 to 7 grains per gallon from the minerals in its report.
Who provides water in Dardenne Prairie?
Dardenne Prairie homes get PWSD 2 or Missouri American Water, depending on the address. The city's utilities page says so.
Do you serve Dardenne Prairie?
Yes. We are based in Wentzville and serve homes on city water across St. Charles County.
Figures for Dardenne Prairie are from PWSD 2 2025 water quality report and Missouri American Water 2025 water quality report, as published on the Missouri Department of Natural Resources website, read on October 27, 2026. Most hardness results are 2023 samples reprinted in the 2025 reports. Last reviewed November 10, 2026.
Find out how hard your water is.
The test is free, it takes place at your kitchen sink, and you see the numbers yourself.