Arnold Water Hardness & Quality Report (2026)

Arnold, Maryland, in Anne Arundel County on the Magothy River arm of the Chesapeake Bay — a Chesapeake Bay waterfront community near Annapolis and the US Naval Academy corridor — receives its municipal water from the Anne Arundel County Department of Public Works water supply system, which draws from the Patuxent River via the Baltimore-Washington supply corridor or from the Severn River watershed reserves. Anne Arundel County's northern communities are served through WSSC purchase agreements and local watershed supply.

The moderately soft 90 mg/L hardness and low TDS of 145.1 mg/L reflect the Piedmont Province watershed character of the Patuxent and Severn River systems serving northern Anne Arundel County. Both the Patuxent River above its Piedmont transition and the Severn River drain the Maryland Piedmont — a terrane of Precambrian Grenville-age gneisses and schists with very limited carbonate contact. These crystalline Piedmont terrains produce naturally soft water, and the finished water at Arnold reflects this clean, soft Piedmont source character.

At 90 mg/L, Arnold's water is moderately soft — comfortable for everyday household use in this Chesapeake Bay community. Scale forms slowly in kettles and appliances over months, soap lathers well, and the dishwasher produces clean results without special treatment. Semi-annual descaling of heating appliances is adequate. The PFAS level of 4.7 ppt is favorable for a Maryland community near the Naval Academy corridor — while Arnold is proximate to the significant PFAS-generating military infrastructure of the Annapolis-Patuxent River naval complex, the Patuxent/Severn watershed's Piedmont headwater character buffers PFAS loading compared to communities drawing directly from military-adjacent groundwater.