The City of O'Fallon's 2025 water quality report shows hardness from 7.2 to 16.5 grains per gallon, depending on which source feeds the street. O'Fallon homes on PWSD 2 get 8.3 to 10.8 grains per gallon. That is hard to very hard on the U.S. Geological Survey scale.
O'Fallon has three water providers. The city system serves about 32,500 people, and other homes are on PWSD 2 or Missouri American Water. Your water bill names yours.
7.2 to 16.5 grains per gallon
123 to 283 mg/L. Hard to very hard.
Range across the city's sources. It depends on which source feeds your street.
The city system serves about 32,500 people. Other O'Fallon homes are on PWSD 2 or Missouri American Water.
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.
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
Sources: City of O'Fallon 2025 water quality report, PWSD 2 2025 water quality report and Missouri American Water 2025 water quality report.
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.
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.
The City of O'Fallon's 2025 water quality report shows hardness from 7.2 to 16.5 grains per gallon, depending on which source feeds the street. O'Fallon homes on PWSD 2 get 8.3 to 10.8 grains per gallon. That is hard to very hard on the U.S. Geological Survey scale.
O'Fallon has three water providers. The city system serves about 32,500 people, and other homes are on PWSD 2 or Missouri American Water. Your water bill names yours.
Yes. We are based in Wentzville and serve homes on city water across St. Charles County.
Figures for O'Fallon are from City of O'Fallon 2025 water quality report, 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.
The test is free, it takes place at your kitchen sink, and you see the numbers yourself.
