DIY: How to Drain a Hot Water Heater

Hot water heating units may need draining at some time or another; this may be due to a number of reasons such as having to replace an old heating unit with a new one or there may be a build-up of sediment in the bottom. Knowing how to drain a hot water heater can save money and time, especially where a plumber can be some time coming. The first step is to turn off any electrical power supply to the unit at the main switch, if it is a gas water heater it will depend on why you are draining it, if it is tank cleaning maintenance the thermostat reading can be adjusted to the pilot setting or the gas can be completely turned off at the valve and then restarted afterwards.

The next step in how to drain a hot water heater is that the water will need to be turned off at the main valve which supplies the heater. This will be the supply line that usually runs to the bottom section of the tank as most tank water heaters fill from the bottom, locate this and follow the water pipe back to where there should be a valve which can be turned off. If you are not sure turn this valve off then go to a sink and turn the hot tap on and there should be no supply in the hot tap coming through. Locate the drain valve on the hot water tank which should be somewhere near the bottom. Drain the heater by attaching a garden hose to the drain valve outlet and diverting the water outside or into a drain.

Once you have the hose on and the heater is draining, turn a hot tap on in the house as this will help to facilitate the draining and avoid any vacuum problems. An easy method for flushing out any sediment may be to leave the main water supply on for a short while, the speed of the cold water running into the bottom of the tank should stir up the water and sediment and this will take a little while to settle allowing enough time to force a good portion of the sediment through the drain valve. This should only take several minutes and once the water flowing through the garden hose has become fairly clean the main supply can be turned off again and the tank drained. Once the tank is empty, shut the drain valve off, do any repairs if they are required then turn the water back on and check for any leaks. Allow the tank to refill, and turn off the hot tap. Switch the power back on or restart the gas and allow the unit to re-heat the contents.