How does St. Charles's water compare to the national average?

The USA national average is 151 mg/L. St. Charles (≈ 0–59 mg/L) is 121 mg/L softer than average.

St. Charles Water Hardness & Quality Report (2026)

Water Hardness

soft

~0–59 mg/L

Soft

estimated · not lab-verified

Source

reservoir

pH Level

8.2

neutral = 7.0

Lead

0.005 mg/L

✓ Below action level

TDS

167 mg/L

Est. Daily Cost

$0.08

energy & soap waste

Source: See methodology section below · Updated 2026

soft~0–59 mg/LSoft · est.

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 4% efficiency due to mineral buildup.

Appliance	In St. Charles	Soft Water City	Efficiency Loss
Kettle	8.2 yrs	8.5 yrs	-4%
Washing Machine	11.5 yrs	12 yrs	-4%
Water Heater	14.4 yrs	15 yrs	-4%

Regional Water Comparison

How St. Charles compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ St. Charles, Maryland	≈ 0–59 mg/L	7.5 ppt	🟢 Soft	reservoir
Saint Charles, Maryland	≈ 120–179 mg/L	10.8 ppt	🟠 Hard	reservoir
Waldorf, Maryland	≈ 120–179 mg/L	10 ppt	🟠 Hard	groundwater
Bennsville, Maryland	≈ 120–179 mg/L	7.4 ppt	🟠 Hard	reservoir
Accokeek, Maryland	≈ 120–179 mg/L	10.4 ppt	🟠 Hard	groundwater

National Benchmark

How St. Charles compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ St. Charles	≈ 0–59 mg/L	🟢 None
USA National Avg	151 mg/L	🟠 Moderate
Scarsdale Top Rated	0.02 mg/L	🟢 None

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What Makes St. Charles's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 167 mg/LpH: 8.2

Charles County Government operates the water utility serving St. Charles (also known as Waldorf) in Charles County, Maryland. The system draws from local groundwater wells, including the St. Charles well and others in the Waldorf Community system (PWS ID 0080049). Treatment occurs at county facilities using disinfection and corrosion control processes. The service area covers residential and commercial zones in the Waldorf area of southern Maryland. The supply relies on confined aquifers rather than surface sources, with the St. Charles well noted as offline in 2020.

The supply originates in the Southern Maryland Coastal Plain watershed, reliant on confined aquifers including the Cretaceous Patuxent aquifer and Tertiary Miocene sands. These formations yield water with low dissolved mineral content because groundwater flows through quartz-rich sands rather than limestone or dolomite-bearing carbonate terrains — keeping calcium and magnesium concentrations low. This geology produces a generally soft water character, distinguishing it from harder inland or northern Maryland supplies shaped by limestone dissolution.

Soft water minimizes scale buildup on fixtures, extending the life of water heaters, dishwashers, and pipes without frequent descaling. Laundry detergents perform efficiently, and soap lathers readily. Routine annual flushing of heaters is still advised to manage sediment; water softeners are unnecessary and could over-treat, potentially introducing corrosion issues. The 2020 Waldorf Community CCR reports full compliance with EPA standards, including no violations for TTHMs or HAA5s (LRAA under limits); treatment involves chlorination with monitoring for bacteria, nitrates, and inorganics.

Geology & Source: Southern Maryland Coastal Plain — Cretaceous Patuxent Formation and Tertiary Miocene sands; quartz-rich sediments lack carbonate contact; low calcium and magnesium yield soft groundwater

Other Maryland Water Reports

Saint Charles

≈ 120–179 mg/L

🟠 Hard

Waldorf

≈ 120–179 mg/L

🟠 Hard

Bennsville

≈ 120–179 mg/L

🟠 Hard

Accokeek

≈ 120–179 mg/L

🟠 Hard

Report an Issue

Notice an error or missing data? Help us keep this page accurate. If you spot incorrect water hardness, outdated utility info, or missing details, please let us know.

All reports are reviewed by our team. Thank you for supporting data quality!

Frequently Asked Questions

Is St. Charles's water safe to drink?

Yes. St. Charles's water meets all federal safety standards. The hardness is ≈ 0–59 mg/L (Soft), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in St. Charles?

St. Charles's water is soft at ≈ 0–59 mg/L. A water softener is generally not necessary, though a carbon filter can improve taste and remove any remaining chlorine.

How does St. Charles compare to the USA average?

The USA national average is 151 mg/L. St. Charles (≈ 0–59 mg/L) is 121 mg/L below the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for St. Charles is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.

Estimated

Water Hardness

Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.

Estimated

Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.

Estimated

TDS — Total Dissolved Solids

Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.

Measured

PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances

EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.

Modelled

Lead

Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.

Calculated

Appliance Lifespan

Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.