Storage water heaters in St. Louis homes quietly collect minerals. Hard water carries dissolved calcium and magnesium, and when the water is heated, some of those minerals come out of solution and settle at the bottom of the tank as sediment. Over time that layer can make the burner or heating element work harder, cause popping or rumbling sounds, and reduce how much hot water you get. A periodic flush is a simple way to clear it out.

Signs your tank may need a flush

  • Popping, ticking, or rumbling sounds while the tank heats
  • Hot water that takes longer to arrive or runs out sooner than it used to
  • Small grit or light specks in the hot water at the tap
  • White flecks collecting in hot-side faucet aerators
  • Water drawn into a glass that looks cloudy

Any of these can have other causes, so treat them as a reason to look, not a diagnosis.

What you need before you start

  • A garden hose long enough to reach a floor drain or an outdoor spot away from walkways
  • A bucket or towels for drips
  • A flashlight, if the area around the drain valve is dim
  • Time for the tank to cool, since hot water can scald

Flushing the tank, step by step

  1. Turn off power to an electric heater at its breaker, or set a gas unit's control to the off or pilot setting.
  2. Close the cold water supply valve on the pipe feeding the top of the tank.
  3. Attach the hose to the drain valve near the bottom of the tank and run the other end to a floor drain or outdoors.
  4. Open a hot tap somewhere else in the house. This lets air in so the tank drains smoothly.
  5. Open the drain valve and let the water run until it comes out clear.
  6. Close the drain valve, remove the hose, then open the cold supply valve. Keep the hot tap open until the flow is steady and free of air spurts.
  7. Close the hot tap, restore power or gas, and check the drain valve for drips.

Let the tank reheat fully before judging the result. A flush removes loose sediment. It does not change how hard your water is, and it cannot remove mineral build-up that is stuck to the tank walls.

St. Louis notes

  • Check your water utility's annual water quality report to learn how hard your supply typically runs. Hardness can vary across the region, so a neighbor's results may not match yours.
  • If your basement floor drain has backed up after heavy rain, do not drain the tank into it. Use an outdoor spot instead.
  • Plan the flush for a day when the space is above freezing, since water left in a hose or valve can freeze in an unheated garage or utility room.

When to stop and call a licensed plumber

  • The drain valve will not close fully or keeps dripping
  • The valve is stuck, and forcing it risks damage
  • Water stays cloudy or gritty after a long flush
  • The tank itself is leaking, or the pressure relief line drips steadily
  • A gas unit smells of gas, or the burner will not light after a reset. If you smell gas, leave the area and contact your gas provider right away.

Keeping sediment under control

Flush the tank on a regular schedule, most simply once a year, and write the date on the tank or in your home records. When a technician services your heater, ask them to check the anode rod and overall tank condition. Keep an eye on hot water performance so you notice changes early.