The amount of time it takes to drain a hot water heater ranges from 15 minutes to one hour depending upon tank size and the amount of debris in the tank. A hot water tank should be drained once every year to remove sediment buildup.
Before draining a hot water heater, allow the water to cool. Attach a garden hose to the hot water heater drain and run it outside. If the hot water tank is located at ground level, gravity drains the tank. If the hot water heater is in the basement, attach the hose to a pump, and use a second hose to route the water outside.