Water hardness in Pennsylvania
Pennsylvania has a median ambient water hardness of 83 mg/L, which is 4.8 grains per gallon and classes as moderately hard. That is the middle of 126,184 samples across 67 counties.
This is ambient water, not tap water. These figures come from samples taken from wells, streams and springs by USGS, EPA and state agencies. Municipal utilities treat, blend and sometimes soften water before it reaches a tap, so a city supply can be considerably softer than the ground beneath it. Treat this as a good guide for a private well and an approximate one for city water. Your utility's annual water quality report gives the real number for a municipal tap, and a test strip gives it for yours.
Every monitored county in Pennsylvania
Ranked hardest first. The middle 50% column shows how much the samples within a county vary, which matters more than the median where a county spans two geologies.
| County | mg/L | gpg | Class | Middle 50% | Samples |
|---|---|---|---|---|---|
| Clarion County | 570 | 33.3 | Very hard | 86 to 1,590 | 3,600 |
| Lebanon County | 242 | 14.1 | Very hard | 98 to 285 | 1,154 |
| Clearfield County | 200 | 11.7 | Very hard | 113 to 657 | 1,756 |
| Lancaster County | 178 | 10.4 | Hard | 97 to 250 | 5,643 |
| Cumberland County | 176 | 10.3 | Hard | 99 to 274 | 1,653 |
| Washington County | 170 | 9.9 | Hard | 128 to 219 | 934 |
| Beaver County | 160 | 9.3 | Hard | 120 to 269 | 1,466 |
| Centre County | 154 | 9 | Hard | 79 to 233 | 2,805 |
| Greene County | 151 | 8.8 | Hard | 108 to 210 | 2,411 |
| Lawrence County | 139 | 8.1 | Hard | 110 to 164 | 1,567 |
| Butler County | 137 | 8 | Hard | 85 to 227 | 499 |
| Mifflin County | 137 | 8 | Hard | 89 to 185 | 1,095 |
| Blair County | 130 | 7.6 | Hard | 90 to 190 | 1,645 |
| Montgomery County | 128 | 7.5 | Hard | 97 to 180 | 1,819 |
| Berks County | 120 | 7 | Moderately hard | 49 to 180 | 2,428 |
| Erie County | 120 | 7 | Moderately hard | 104 to 153 | 1,718 |
| Philadelphia County | 120 | 7 | Moderately hard | 73 to 170 | 4,003 |
| Lehigh County | 113 | 6.6 | Moderately hard | 77 to 160 | 1,000 |
| Jefferson County | 110 | 6.4 | Moderately hard | 59 to 154 | 901 |
| Westmoreland County | 109 | 6.4 | Moderately hard | 65 to 167 | 1,365 |
| Chester County | 100 | 5.8 | Moderately hard | 64 to 165 | 6,264 |
| York County | 100 | 5.8 | Moderately hard | 58 to 134 | 3,277 |
| Allegheny County | 99 | 5.8 | Moderately hard | 80 to 126 | 3,608 |
| Indiana County | 96 | 5.6 | Moderately hard | 55 to 150 | 1,153 |
| Huntingdon County | 93 | 5.4 | Moderately hard | 66 to 130 | 1,777 |
| Dauphin County | 90 | 5.3 | Moderately hard | 64 to 122 | 3,558 |
| Franklin County | 90 | 5.3 | Moderately hard | 29 to 170 | 581 |
| Mercer County | 90 | 5.3 | Moderately hard | 75 to 112 | 772 |
| Delaware County | 88 | 5.1 | Moderately hard | 68 to 109 | 1,306 |
| Perry County | 88 | 5.1 | Moderately hard | 64 to 114 | 1,984 |
| Bucks County | 86 | 5 | Moderately hard | 63 to 130 | 3,425 |
| Schuylkill County | 85 | 5 | Moderately hard | 45 to 147 | 5,887 |
| Northumberland County | 84 | 4.9 | Moderately hard | 60 to 128 | 2,790 |
| Montour County | 82 | 4.8 | Moderately hard | 62 to 120 | 1,385 |
| Union County | 80 | 4.7 | Moderately hard | 14 to 104 | 946 |
| Lackawanna County | 79 | 4.6 | Moderately hard | 47 to 140 | 1,041 |
| Armstrong County | 77 | 4.5 | Moderately hard | 60 to 101 | 1,592 |
| Snyder County | 77 | 4.5 | Moderately hard | 60 to 100 | 573 |
| Luzerne County | 73 | 4.3 | Moderately hard | 33 to 110 | 1,525 |
| Bedford County | 72 | 4.2 | Moderately hard | 28 to 141 | 1,547 |
| Crawford County | 72 | 4.2 | Moderately hard | 60 to 100 | 1,104 |
| Cambria County | 65 | 3.8 | Moderately hard | 32 to 240 | 385 |
| Fayette County | 64 | 3.7 | Moderately hard | 31 to 120 | 2,416 |
| Venango County | 62 | 3.6 | Moderately hard | 49 to 85 | 1,369 |
| Bradford County | 59 | 3.4 | Soft | 40 to 89 | 2,022 |
| Northampton County | 58 | 3.4 | Soft | 33 to 114 | 2,320 |
| Susquehanna County | 57 | 3.3 | Soft | 32 to 80 | 794 |
| Tioga County | 57 | 3.3 | Soft | 37 to 80 | 1,623 |
| Wyoming County | 52 | 3 | Soft | 39 to 70 | 1,259 |
| Clinton County | 40 | 2.3 | Soft | 17 to 119 | 3,613 |
| Elk County | 40 | 2.3 | Soft | 26 to 100 | 364 |
| Warren County | 40 | 2.3 | Soft | 23 to 82 | 2,018 |
| Fulton County | 36 | 2.1 | Soft | 23 to 62 | 538 |
| Juniata County | 36 | 2.1 | Soft | 20 to 68 | 273 |
| Columbia County | 31 | 1.8 | Soft | 23 to 50 | 644 |
| Lycoming County | 30 | 1.8 | Soft | 22 to 49 | 4,154 |
| Cameron County | 29 | 1.7 | Soft | 21 to 46 | 1,024 |
| Somerset County | 29 | 1.7 | Soft | 14 to 46 | 2,852 |
| McKean County | 26 | 1.5 | Soft | 20 to 37 | 1,350 |
| Potter County | 25 | 1.5 | Soft | 18 to 39 | 922 |
| Monroe County | 24 | 1.4 | Soft | 16 to 39 | 1,834 |
| Wayne County | 23 | 1.3 | Soft | 19 to 30 | 2,402 |
| Forest County | 21 | 1.2 | Soft | 15 to 48 | 881 |
| Pike County | 20 | 1.2 | Soft | 15 to 24 | 3,424 |
| Sullivan County | 20 | 1.2 | Soft | 10 to 28 | 535 |
| Adams County | 17 | 1 | Soft | 6 to 96 | 541 |
| Carbon County | 17 | 1 | Soft | 9 to 36 | 1,070 |
Source: Water Quality Portal (USGS, EPA and state agencies), waterqualitydata.us, retrieved 2026-09-19. 2,904,346 samples across 3,110 counties.
What this means for a household in Pennsylvania
At 4.8 grains per gallon, a family of four would need a softener of about 16,000 grains to regenerate roughly weekly, using around 197 lb of salt a year. Size it for your own household.
67 of these counties include well samples, so the figures are a reasonable guide for private well water there. Municipal supplies in the same counties may be softer, because utilities often blend or treat.
Hardness follows geology rather than borders. Where a county sits on limestone or dolomite the water is hard; on granite, basalt or sandstone it is soft. That is why neighbouring counties in this table can differ by a factor of several.