The water in Herndon, by the numbers
Source: Town of Herndon (Fairfax Water's water) water quality report; U.S. Census Bureau, American Community Survey 2020 to 2024, median year built; U.S. Geological Survey, Hardness of Water.
What it means for your water heater
Hard water carries calcium and magnesium. Heat a tank of it and some drops out as sediment on the bottom, under the burner or the lower element. That's what makes a water heater rumble and pop, take longer to recover and wear out early. Flushing it once a year clears it out.
- Popping or rumbling while it heats. That is water boiling under a layer of sediment.
- Grit in the faucet screens on the hot side.
- A drain valve nobody has opened since the house was sold.
A tankless gets descaled instead. Navien's manual calls for it once a year wherever the water runs 4 grains per gallon or harder with no softener, and the water in Herndon does. Descaling is $300, regularly $350.
Half the owner-occupied homes in Herndon were built before 1981. A house that age can still have its original shutoff valves and supply lines, which is why every flush comes with the plumbing safety check: supply hoses, shutoff valves, water pressure and drains, with photos of anything worth knowing about.
More on the flush in Herndon on SwiftPro's Herndon water heater flush page.
The rest of the water in Herndon
Hardness is one line of Town of Herndon (Fairfax Water's water)'s testing. The full Town of Herndon (Fairfax Water's water) water report shows every contaminant it found, next to the legal limit and the health guideline. On a private well, a test at your own tap is the number that counts.
Nearby towns
Questions people ask
Is Herndon water hard?
How often should I flush my water heater in Herndon?
How much is a water heater flush in Herndon?
Get it flushed for $99.
Normally $199, with the plumbing safety check included. Tankless descaling is $300, regularly $350. Pick a time online, and you pay after the visit.