You can make your water heater more efficient and extend its life by draining the tank and flushing away sediment at least once a year. Here’s all you have to do.
For electric heaters, turn off the power at the breaker box. For gas units, turn the fuel control to the off setting.
Next, turn off the cold water inlet valve, and attach a garden hose to the outlet valve at the bottom of the tank. When you open the outlet valve, be careful; it is hot water, after all.
To get the water flowing, you also have to flip the pressure relief valve near the top of the tank to break the vacuum inside.
Once the hot water drains, open the cold water valve to flush out the tank, and then simply reverse the process to restore normal operation.