How hard is the water in Baltimore County, MD?
5.8 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Baltimore County, MD is 99 mg/L as calcium carbonate, which is 5.8 gpg. That is moderately hard on the USGS scale. It comes from 534 samples at 248 sites between 1990 and 2019, 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 2.6 and 13.5 gpg. That spread crosses a decision line, so some homes here land on a different answer. A $10 test strip on your own tap settles it. Confidence in the county figure: high (how it is measured).
What to do next
At 5.8 gpg this is your call. Look for white film on glasses and crust on the shower head: if you see little of either, you can live without one. If you do want one, a 24,000-grain unit is enough, so ask for that size rather than a bigger one. Because Baltimore County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on when a softener is not worth it.
From 0.4 to 35.7 gpg
The softest single sample on record in Baltimore County was 6.6 mg/L and the hardest 610.5 mg/L, a 93-fold gap. The top quarter of sites read above 13.5 gpg and the bottom quarter below 2.6 gpg.
Wells 5.8 gpg, rivers and lakes 8.5 gpg
534 groundwater samples from 248 wells put the median at 98.7 mg/L. 78 surface samples from 27 sites put it at 145 mg/L. In Baltimore County the rivers and lakes come out 2.7 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. The two sources are close, so the county figure should hold whichever one your tap is on.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 126 lb of salt a year (4 bags of 40 lb, about $23), 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 $123 a year.
Sizing at 5.8 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 348 | 24,000 | 42 lb |
| 2 | 696 | 24,000 | 85 lb |
| 4 | 1,392 | 24,000 | 169 lb |
| 6 | 2,088 | 24,000 | 254 lb |
Baltimore County against the rest of Maryland
Among the 24 Maryland counties with data, Baltimore County is number 8 of 24 counting from the hardest. Across the whole country it is harder than 34% of counties.
Softest in Maryland: Charles County at 0.3 gpg. Hardest: Washington County at 18.5 gpg. Closest to Baltimore County: Dorchester County (5.6), Montgomery County (6.4), Carroll County (6.4).