St. Charles Water Hardness & Quality Report (2026)
Water Hardness
8.1 grains per gallon
Source
reservoir
pH Level
7.9
neutral = 7.0
Lead
0.005 mg/L
✓ Below action level
TDS
289.8 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 St. Charles, your appliances are currently losing 18% efficiency due to mineral buildup.
| Appliance | In St. Charles | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5 yrs | 8.5 yrs | -41% |
| Washing Machine | 8.5 yrs | 12 yrs | -29% |
| Water Heater | 10.1 yrs | 15 yrs | -33% |
Regional Water Comparison
How St. Charles compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ St. Charles, Maryland | 138.5 mg/L | 7.5 ppt | 🟠 Hard | reservoir |
| Saint Charles, Maryland | 196 mg/L | 10.8 ppt | 🔴 Very Hard | reservoir |
| Waldorf, Maryland | 182 mg/L | 10 ppt | 🔴 Very Hard | reservoir |
| Fort Washington, Maryland | 98.5 mg/L | 5.2 ppt | 🟡 Moderately Hard | reservoir |
| Clinton, Maryland | 178 mg/L | 9.7 ppt | 🟠 Hard | reservoir |
National Benchmark
How St. Charles compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ St. Charles | 138.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes St. Charles's Water Unique?
Local geology and source profile
St. Charles, Maryland, an unincorporated planned community in Charles County — a major south Charles County planned community (St. Charles is a massive planned community development in the Waldorf area of Charles County — originally conceived in the 1960s and 1970s as one of the large-scale planned communities in the mid-Atlantic region, comparable to Columbia, Maryland; St. Charles encompasses multiple distinct community villages in the south Charles County Waldorf corridor), a diverse Charles County community with a significant African-American, federal workforce, and military professional population (Charles County is home of Joint Base Andrews and Naval Support Facility Indian Head, and has a significant military and federal contractor population), adjacent to Waldorf (the primary commercial center of Charles County), and one of the fastest-growing areas in the Baltimore–Washington metropolitan area — draws its municipal water supply via the WSSC Water or Charles County water system. Water hardness in St. Charles measures 138.5 mg/L — classified as moderately hard.
St. Charles's moderate hardness reflects the Charles County water supply characteristics. The south Charles County water system distributes the Potomac River supply (Maryland Piedmont calcareous-moderate) through the Waldorf–St. Charles area mains, producing the moderate 138.5 mg/L.
At 138.5 mg/L, St. Charles residents encounter moderate scale accumulation. Monthly cleaning with citric acid solution is recommended. Charles County water systems consistently deliver water meeting all Maryland MDE and EPA Safe Drinking Water Act requirements.
Geology & Source: River supply from the Potomac River via the Washington Suburban Sanitary Commission (WSSC Water) or Charles County water — the Charles County south Maryland DC suburban Waldorf corridor (Precambrian–Paleozoic calcareous-moderate Virginia–Maryland Piedmont supply — the south Charles County Waldorf–St. Charles WSSC or Charles County distribution zone); moderately hard supply at 138.5 mg/L in Charles County.