Ilchester Water Hardness & Quality Report (2026)

Ilchester, Maryland, in Howard County along the Patapsco River in the historic mill village corridor between Ellicott City and Catonsville — one of Maryland's most picturesque riverside communities, a former 19th-century textile mill town now protected within Patapsco Valley State Park — receives its municipal water from Baltimore City Bureau of Water and Wastewater or Howard County DPW, accessing the Baltimore system supply that draws from the Liberty Reservoir on the North Branch Patapsco River and the Prettyboy and Loch Raven reservoirs on the Gunpowder system.

The moderately hard 143 mg/L hardness and TDS of 304.8 mg/L reflect the Patapsco River basin's mixed Piedmont and Valley and Ridge geological character. Liberty Reservoir impounds the North Branch Patapsco River and its tributaries in Carroll County — a watershed that drains the Maryland Piedmont Province over Precambrian gneiss and schist in its lower reaches, with the upper Carroll County watershed approaching the Valley and Ridge boundary where Ordovician Limestone and Cambrian Carbonate formations are present. This moderate carbonate contact in the upper Patapsco basin contributes calcium and magnesium to the Liberty Reservoir supply, producing finished water somewhat harder than the pure Piedmont Patuxent supply.

At 143 mg/L, Ilchester's water is moderately hard — characteristic of the Baltimore metropolitan area supply. Scale forms gradually in kettles and appliances over months, the dishwasher benefits from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling of heating appliances is the standard schedule. The PFAS level of 7.7 ppt warrants a certified drinking water filter — Howard County's technology and defense corridor along the Route 29 and US-1 industrial zones contributes to the regional PFAS background.