How to Flush a Water Heater

Sediment is the silent performance killer of every residential water heater. Over time, minerals from your water supply settle at the bottom of the tank, creating a layer of crust that insulates the water from the burner or heating element. If you hear rhythmic popping, cracking, or rumbling sounds while the water heats, you are listening to steam bubbles trapped beneath a layer of mineral sludge. Flushing the tank once a year is the single most effective way to extend the life of your appliance. A clean tank heats water faster, uses less energy, and avoids the premature tank failure that sediment hotspots often cause. This is a straightforward task that requires nothing more than a standard garden hose and a bit of patience, and it is easily handled by any homeowner.

  1. Kill the Power First. Turn off the circuit breaker for electric heaters or turn the gas control valve to the pilot setting for gas models. You must prevent the heating elements from firing while the tank is empty to avoid permanent damage.
  2. Route the Escape Path. Attach a standard garden hose to the drain valve located at the base of the tank. Run the other end of the hose to a floor drain, a basement sump, or outside to a safe location.
  3. Break the Vacuum Seal. Open a hot water faucet somewhere in the house to allow air into the system. This breaks the vacuum seal and ensures the water drains smoothly without stalling.
  4. Open the Floodgates Slowly. Open the drain valve slowly using a screwdriver or the built-in handle. Watch for sediment-filled, discolored water to flow out of the hose.
  5. Pulse and Purge the Crud. Once the water stops flowing, briefly turn the cold water supply back on to agitate any remaining sediment at the bottom. Repeat this cycle of draining and flushing until the water exiting the hose runs completely clear.
  6. Refill and Restore Power. Close the drain valve, disconnect the hose, and turn the cold water supply back on to fill the tank. Keep the hot water faucet in the house open until a steady stream of water flows without sputtering or air pockets.