Water heater flush in Delaplane.

Most flush pages start with the water company’s hardness number. Delaplane doesn’t have a water company to ask. FCWSA, Fauquier’s water authority, lists sixteen systems in its 2025 report and none of them reaches 20144; the nearest draws from two wells up Route 17 in Paris. Your water comes up from your own well, nobody publishes a hardness figure for it, and the only number that counts is the one from a test of your own tap.

What’s in that water starts in the rock. Under the village, the geologic map shows Cobbler Mountain alkali feldspar quartz syenite, a hard crystalline rock, and the U.S. Geological Survey finds groundwater levels lowest in the crystalline Blue Ridge rock of Fauquier’s northwest. FCWSA says groundwater in the county runs down through the summer and starts recharging around October 1, and that its own wells can turn out harder water, or water tinted by natural iron and manganese, when they pump long hours in summer. Whatever a well brings up settles on the floor of the tank, right over the burner or the lower element.

Virginia Cooperative Extension’s Fauquier well clinics give the closest thing to a local picture: 97 household samples from 2012 to 2017, where low pH, iron and manganese were among the most common problems. In a heated tank, iron settles as orange-brown silt and manganese as black specks, and a flush carries both out the drain valve. Acidic water can also wear the tank’s anode rod faster, so the flush includes a look at it. Most clinic households already had some treatment, usually a sediment filter, which stops sand but not iron dissolved in the water.

How the house gets used matters too. The state’s 2004 survey of the Crooked Run Valley, Delaplane included, found many of its late twentieth century houses lived in only on weekends or by season, and a tank that sits for weeks between visits still gathers sediment, with nobody around to hear it rumble. In the three houses in ten heated by electricity the water heater is usually electric as well, and its lower element is the first part to get buried. On a propane tank, the burner and its flue get a look while it’s drained.