How hard is the water in Penobscot County, ME?
6.9 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Penobscot County, ME is 118 mg/L as calcium carbonate, which is 6.9 gpg. That is moderately hard on the USGS scale. It comes from 12 samples at 9 sites between 1990 and 2014, 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 3.5 and 7.4 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: medium (how it is measured).
What to do next
At 6.9 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 Penobscot 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 16.2 gpg
The softest single sample on record in Penobscot County was 6.6 mg/L and the hardest 278 mg/L, a 42-fold gap. The top quarter of sites read above 7.4 gpg and the bottom quarter below 3.5 gpg.
Wells 6.9 gpg, rivers and lakes 1.3 gpg
12 groundwater samples from 9 wells put the median at 118 mg/L. 20 surface samples from 2 sites put it at 22.7 mg/L. In Penobscot County the wells come out 5.6 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 151 lb of salt a year (4 bags of 40 lb, about $27), 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 $127 a year.
Sizing at 6.9 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 414 | 24,000 | 50 lb |
| 2 | 828 | 24,000 | 101 lb |
| 4 | 1,656 | 24,000 | 201 lb |
| 6 | 2,484 | 24,000 | 302 lb |
Penobscot County against the rest of Maine
Among the 16 Maine counties with data, Penobscot County is the hardest. Across the whole country it is harder than 38% of counties.
Softest in Maine: Lincoln County at 0.7 gpg. Closest to Penobscot County: York County (6.4), Aroostook County (6.4), Knox County (4.3).