How hard is the water in Washington County, MD?

18.5 grains per gallon

A softener will pay its way here.

The median hardness measured in Washington County, MD is 317 mg/L as calcium carbonate, which is 18.5 gpg. That is very hard on the USGS scale. It comes from 77 samples at 20 sites between 1990 and 2022, drawn from groundwater wells, which is what most taps and private wells in the county draw on.

How much it varies here

Half the sites came in between 15.7 and 20.3 gpg. The whole middle of that range gives the same answer, so a test of your own tap is unlikely to change it. Confidence in the county figure: high (how it is measured).

What to do next

At 18.5 gpg a softener pays its way here. Before you buy, check the quoted unit's grain capacity against the sizing table below, and ask whether it regenerates on demand, which uses less salt than a timer. Call your utility for its own report if you are on city water.

More on sizing a softener for your household.

From 0.9 to 23.6 gpg

The softest single sample on record in Washington County was 14.7 mg/L and the hardest 404 mg/L, a 27-fold gap. The top quarter of sites read above 20.3 gpg and the bottom quarter below 15.7 gpg. So even here some sites draw water soft enough to need nothing at all.

Wells 18.5 gpg, rivers and lakes 4.6 gpg

77 groundwater samples from 20 wells put the median at 316.8 mg/L. 830 surface samples from 22 sites put it at 79 mg/L. In Washington County the wells come out 13.9 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. A utility here that draws from the river can deliver noticeably different water from a private well next door.

What a softener would cost to run

For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 404 lb of salt a year (11 bags of 40 lb, about $73), and roughly 2,346 gallons of regeneration water. Installed, most units run $1,000 to $4,500; spread over 15 years with salt, that is about $173 a year.

Sizing at 18.5 gpg

Washington County against the rest of Maryland

Among the 24 Maryland counties with data, Washington County is the hardest. Across the whole country it is harder than 80% of counties.

Softest in Maryland: Charles County at 0.3 gpg. Closest to Washington County: Allegany County (12.8), Frederick County (9), Baltimore city (7.6).