Erie Water Hardness & Quality Report (2026)

Erie, Pennsylvania, on the south shore of Lake Erie, draws its municipal water supply from Lake Erie via the Erie Water Works, operating an intake at the Presque Isle Bay area in Erie County, Pennsylvania. Lake Erie is the fourth-largest Great Lake and the shallowest — with the smallest volume of any Great Lake — making it the most responsive to watershed mineral inputs. Water is treated at the Erie Water Works Treatment Plant before distribution throughout Erie County. Water hardness measures 105.5 mg/L — classified as moderately hard.

Erie's moderate hardness reflects Lake Erie's water chemistry at the Pennsylvania south shore. Lake Erie receives drainage from the Appalachian Plateau of New York, Pennsylvania, and Ohio — terrain underlain by Devonian Hamilton Group calcareous shale and limestone, Devonian Onondaga Limestone, Silurian Lockport Dolomite (the Niagara Escarpment formation), and Mississippian Bedford Shale in the eastern Ohio watershed. While Lake Erie is shallower and more biologically productive than the other Great Lakes, its mineral content is slightly moderated by inflow from softer Appalachian plateau drainage in the eastern watershed. Erie County's 105.5 mg/L reading is consistent with moderate Great Lakes hardness at the Pennsylvania shore.

With hardness at 105.5 mg/L, Erie residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. Dishwashers produce cleaner glassware with rinse-aid. Erie Water Works consistently delivers water meeting all Pennsylvania DEP and EPA Safe Drinking Water Act requirements.