Saint Peters Water Hardness & Quality Report (2026)
Water Hardness
8 grains per gallon
Source
river
pH Level
7.8
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
250.4 mg/L
Est. Daily Cost
$0.37
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Saint Peters, your appliances are currently losing 18% efficiency due to mineral buildup.
| Appliance | In Saint Peters | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.1 yrs | 8.5 yrs | -40% |
| Washing Machine | 8.5 yrs | 12 yrs | -29% |
| Water Heater | 10.1 yrs | 15 yrs | -33% |
Regional Water Comparison
How Saint Peters compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Saint Peters, Missouri | 137 mg/L | 4.6 ppt | 🟠 Hard | river |
| O'Fallon, Missouri | 279 mg/L | 8.3 ppt | 🔴 Very Hard | river |
| Dardenne Prairie, Missouri | 289.5 mg/L | 8.5 ppt | 🔴 Very Hard | river |
| Chesterfield, Missouri | 107.5 mg/L | 3.9 ppt | 🟡 Moderately Hard | river |
| Saint Charles, Missouri | 104 mg/L | 3.8 ppt | 🟡 Moderately Hard | river |
National Benchmark
How Saint Peters compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Saint Peters | 137 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Saint Peters's Water Unique?
Local geology and source profile
St. Peters, Missouri, in St. Charles County west of St. Louis — one of Missouri's fastest-growing cities, a major St. Louis west suburban community with significant corporate and residential development along I-70 and Mid Rivers Mall Drive — draws its municipal water supply from the Missouri River via Missouri American Water Company St. Charles County distribution. Water hardness in St. Peters measures 137 mg/L — classified as moderately hard.
St. Peters' moderate hardness reflects the Missouri River's calcareous St. Charles County watershed. The Missouri River at St. Charles–St. Peters drains the upper Missouri basin (calcareous Great Plains terrain — the Nebraska–Kansas calcareous loess and Cretaceous Pierre Shale) and the immediate St. Charles County Missouri River terrace (Mississippian–Pennsylvanian calcareous cyclothemic limestone of the Missouri Ozark border). Missouri American Water's treatment and the relatively newer St. Charles County distribution infrastructure (developed primarily in the 1970s–2000s during St. Peters' rapid suburban build-out) maintain the supply at the moderate 137 mg/L — softer than older Missouri River distribution zones.
At 137 mg/L, St. Peters residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. Missouri American Water Company consistently delivers water meeting all Missouri DHSS and EPA Safe Drinking Water Act requirements.
Geology & Source: River supply from the Missouri River and Creve Coeur Lake via the Missouri American Water Company St. Charles County distribution — the St. Charles County Missouri River Valley draining the Mississippian–Pennsylvanian calcareous cyclothems and the Missouri River calcareous alluvial terrace; moderately hard supply at 137 mg/L in St. Charles County.