How to drain a hot water heater

A water heater needs to be properly drained as part of its regular maintenance. Over time, sediment builds up in the bottom of a water heater, which can lead to clogs, says The Family Handyman. Draining a water heater helps flush out this sediment, usually made up of minerals and other debris, that may cause it to malfunction, says HGTV. If you do not properly maintain your water heater, it may not work efficiently or could simply stop working at all.

It's generally a good idea to drain your water heater at least once a year, according to both Bob Vila and Family Handyman. If you live in an area with hard water (that has high mineral content), Angi recommends you may want to drain it every six months, or so. Remember, always check your owner's manual to see what the manufacturer recommends.

To drain your water heater, you'll typically need the following tools, The Spruce recommends:

• Garden hose: You'll need a garden hose to connect to the drain valve at the bottom of the water heater to allow the water to drain out.
• Flat-head screwdriver or water heater drain valve key: Most water heater drain valves have a flat-head slot or a square/hexagonal opening that needs a special drain valve key to open it.
• Bucket or drain pan: Place a large bucket or drain pan near the drain valve to catch any water that may spill out initially when opening the valve.

Additionally, some optional items you may consider having before you start:

• Non-contact voltage tester: It's a good idea to use a non-contact voltage tester to ensure the power to the water heater is turned off before draining it.
• Pliers or wrench: If the drain valve is stuck or difficult to turn, you may need a pair of pliers or a wrench to provide extra leverage.
• Wet/dry vacuum: If you need to drain the water heater in a location where a garden hose cannot reach a floor drain, you may need a wet/dry vacuum to suction any excess water.

The DIY Network suggests the following steps on how to drain a water heater. (For specific information on your water heater, be sure to read the owner's manual.) If you're uncomfortable performing this type of maintenance on your water heater, call a plumber and schedule a professional draining.

Step 1: Shut off the water to your water heater

At the top of the water heater, you'll see a water pipe and a shutoff valve going into the water heater. Turn this valve to shut off the water to the tank.

Step 2: Turn off the power to the water heater

It's important to shut off the power to your water heater before draining it, or you could potentially burn out the heating elements. If you have an electric water heater, shut the power off from your home's electrical panel. The correct fuse or circuit breaker should be labeled as being connected to the water heater.

If it's a gas water heater, HGTV says you can turn the water heater's thermostat to "pilot" for this step. Or, The Family Handyman says to shut off the gas supply to the heater. Check your owner's manual and follow the instructions provided for your specific water heater.

Step 3: Give the water time to cool off

The water in your water heater is extremely hot. To help prevent injury, it's a good idea to let your water heater sit overnight so the water within the tank cools down before you drain it. (Bob Vila says you should wait a few hours at the very least. Taking a hot shower can also help speed up the cooling process.)

Step 4: Attach a hose to the drain valve

Once your water heater has cooled down, place one end of a hose (you can use a garden hose) into a floor drain or, if it will reach, directly outside. Attach the other end onto the drain valve at the bottom of the water heater.

Step 5: Turn on a hot water faucet

Open the hot water tap, like a sink faucet, that is nearest to the water heater. This helps to alleviate pressure and allows the tank to drain quicker. If possible, the DIY Network recommends using a tap that is on the floor above the water heater.

Step 6: Open the drain valve (let the water out)

Once you open this valve, the water will begin to flow out of the tank. Be patient, as it may take a while to drain if the tank was full or there is a lot of sediment.

Step 7: Flush the tank with fresh water

With the drain valve still open, turn the cold water back on to help eliminate any remaining sediment on the bottom of the tank. Repeat this step until the water runs clear. Then, turn the water valve off again.

Step 8: Refill the tank

Remove the hose from the drain valve, and be sure to close the valve. Turn the water supply back on to start refilling the tank. Once the tank is full, turn the power or gas supply to the water heater back on. Remember to turn off the faucet you turned on earlier while draining the tank.

The process for draining different types of water heaters is typically similar but it can vary by a step or two, depending on which kind you have in your home.

How to drain electric water heater

Follow all 8 steps outlined above, including turning off the power to your water heater from the breaker and checking that the power is turned off before you drain it.

How to drain a gas water heater

Follow the 8 steps outlined above. Be sure to turn off the gas supply before draining the heater.

Draining tankless water heaters

These don't have a large tank to drain, but you'll still need to check and/or flush the system annually, explains Wagner Mechanical. Tankless water heaters may require you to have additional tools for you to complete this properly and safely. The process involves shutting off the water and power supplies, connecting pump pliers to the hot and cold-water lines to create a cross-over flow, and allowing water to flow out the hot water side until it runs cold and clear.

So, while the overall premise of shutting off utilities, relieving pressure, and draining/flushing remains the same, there are some differences in prep work needed based on the kind of water heater you have. Checking the manufacturer's instructions is always advised before draining any type of water heater.

If you don’t drain or flush your hot water heater, minerals and sediments from the water supply will settle at the bottom of the tank. This buildup can create a separation between the water and the heat source, explains Angi, which can decrease efficiency and increase the cost to heat the water. If the water heater is not drained for years, this buildup can cause a decrease in the tank capacity.

Additionally, when sediment builds up, it can lead to corrosion inside the tank that can cause leaks or failure if left unchecked for too long. Corrosion can also affect the components inside of the tank, which is why regular flushing/draining is typically recommended.

What does noise from the water heater mean?

As sediment hardens, it can get baked onto the tank bottom (especially from hard water), explains Mr. Rooter. This insulating layer can cause popping, cracking or rumbling noises as the water is heated. Or, noise from your water heater can be the result of rust forming inside of the tank, which is typically a result from not regularly flushing the sediment.

Water heaters are usually a fairly low maintenance appliance, but remembering to drain yours regularly is key. This may help keep it running efficiently for longer and keep your water heating costs down.