Water heater flush in Purcellville.

Inside the town limits, about half your water comes from the J.T. Hirst Reservoir at the foot of the Blue Ridge, filled by Harris, Potts and Cooper Springs and treated at the Town’s plant north of town. The rest comes from eleven Town wells, from the Forbes and Kane wells to the one at Village Case. The Town’s 2025 water quality report covers what’s regulated, and hardness isn’t on the list, so there’s no published grains-per-gallon figure to set a schedule by.

Without a number, go by what the heater tells you. The Town’s source water plan puts its wells in the igneous and metamorphic rock of the Blue Ridge, and groundwater picks up dissolved minerals that drop out when the water is heated. A tank that pops or rumbles, or a tankless throwing scale codes, has enough in it to flush. A hardness test at the kitchen tap settles the rest: above about 4 grains a gallon with no softener, Navien asks for a tankless descale every year.

Out on the county side of 20132, most homes have their own well, and nobody tests that water but you. Unfiltered well water can bring fine sand and silt along with the minerals, and all of it lands on the floor of the tank. The well and its pump are a well company’s job. The heater is ours: drained, rinsed until the water runs clear, the anode rod looked at, the relief valve tested.

Propane heats close to half the homes on the county side and about a third inside the town, so plenty of Purcellville water heaters burn propane, and on one of those the flush comes with a look at the burner and the flue. In the town’s electric-heat homes, about half of them, the tank is usually electric, and sediment buries its lower heating element first. A tank that came with a 2001 house has most likely been replaced once already, so the one there now may be ten or so, the age when a flush and an anode check do the most.