If there is dirty water coming from your hot water taps but your cold water taps are clear, you may need to flush out your hot water tank. If so, these instructions will generally apply to hot water tanks properly installed within the last 10 to 15 years. If you have any problems following these instructions, you should contact a plumber to help you in flushing your hot water tank.
Turn off the power to the hot water tank. Caution: Power must be off before draining the hot water tank. The tank will be substantially damaged if there is no water in it and the power is on.
Connect a hose to the drain valve and direct it to a floor drain.
Open the drain valve and flush the tank for about five minutes. Caution: At first, the water will be very hot.
Shut off the cold water inlet.
Open several hot water taps in the house to let air into the line in order to completely drain the tank.
Turn the cold water inlet back on.
Carefully close the drain valve as much as possible without forcing this valve shut. Due to age and possible rust in the valve, it may be difficult to shut it drip tight. Open the hot water supply valve to fill the tank, purging air through the open hot water taps.
Open the drain valve again and flush until the water is running clear.
Carefully shut the drain valve and the hot water taps in the house.