Flushing your water heater once a year is the cheapest thing you can do to make it last longer, and in Prince William County it matters more than most places. Here is why, and exactly how to do it.

Why it matters here

Prince William Water classifies most of the area’s supply as moderately hard, and some systems as outright hard. Hard water carries dissolved minerals that settle to the bottom of your tank as sediment. Over time that sediment layer insulates the burner or heating element from the water, so the heater runs longer and costs more, takes longer to recover, and wears out sooner. Flushing clears it out. If hard water is a recurring headache in your home, our guide to hard water in Northern Virginia covers the bigger picture.

Signs you are overdue

Listen for rumbling, popping, or crackling from the tank, which is water bubbling up through a sediment layer. Other tells are hot water running out faster than it used to, a longer wait for it to reheat, and cloudy or sandy-looking hot water.

How often to flush

Once a year is standard. If your water is on the harder end of the county, or the tank has never been flushed, do it twice in the first year and then settle into an annual rhythm.

How to flush a tank water heater, step by step

Safety first: the water in the tank is scalding, so give it time to cool, and never run an electric heater’s elements without water around them.

  1. Turn off the heater. On electric, switch off its breaker. On gas, turn the gas control to “pilot” or “vacation.”
  2. Close the cold water supply valve at the top of the tank.
  3. Let the water cool for an hour or two if you can. This is the scald-safety step.
  4. Connect a garden hose to the drain valve at the base and run the other end to a floor drain, a utility sink, or outside downhill.
  5. Open a hot water tap somewhere in the house so air can get in and the tank drains smoothly.
  6. Open the drain valve and let the tank empty.
  7. With the hose still draining, open the cold supply in short bursts to stir up the settled sediment and carry it out. Repeat until the water runs clear.
  8. Close the drain valve and remove the hose.
  9. Turn the cold supply back on. When a hot tap upstairs runs a steady stream with no sputtering, the tank is full.
  10. Only now restore power or gas. On electric especially, the elements must be underwater first.

If it goes sideways

If the drain valve will not reseal, the water never runs clear, or you cannot get the tank refilled and running, stop and call. A stuck valve, or a tank so packed with hardened sediment that it will not clear, is a sign we should take a look and help you decide whether it is worth repairing or replacing.

Tankless is different

If you have a tankless unit, it is not flushed the same way, it is descaled, and with our water hardness that descaling is more important, not less. Here is our take on whether tankless is worth it in Prince William County.

Fifteen minutes once a year buys you efficiency and years of tank life. Put it on your fall list. Serving Woodbridge, Dale City, Lake Ridge, and Prince William County. Schedule water heater service →