Flushing

• Before flushing a gas hot water tank, make sure you turn the gas valve knob to the pilot position. Attach a garden hose to the drain valve on the tank and place the end of the hose in a drain or outside. Open the drain valve and flush the tank for at least five minutes.
  
  

Draining

• Next, close the drain valve and shut off the water at the cold water inlet. Turn on a hot water tap in the house and open the drain valve on the tank to drain the tank. It may take from 30 minutes to one hour for the tank to completely drain.
  
  

Filling

• After draining the tank, turn the cold water tap on and off until the water runs clear to flush the sediment from the tank. Close the drain valve on the tank and turn the cold water inlet on the tank on to refill the tank, while keeping the hot water tap on. When a steady flow of water runs from the hot water tap, the tank is full and you can turn the water tap off. Turn the gas valve knob on the tank back on, turn the drain valve off and unfasten the garden hose.