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How to Drain a Hot Water Tank?

Table of Contents

Most water heaters use a large insulated tank to ensure that there is always plenty of hot water available for various purposes in the home. Over time, minerals in the water, as well as sand and gravel from the city water supply, can settle to the bottom of the tank. This sediment can reduce the efficiency and capacity of your water heater. It can also clog the drain and interfere with ongoing maintenance, leading to early failure. Draining your water heater to remove sediment is a simple DIY, requiring very little time and just a few basic tools.

Sediment can impair the efficiency of the gas water heater burner and cause crackling and noise during heating cycles. Depending on your water source and mineral content, gas and electric water heaters should be flushed for sediment every one to two years to ensure optimal performance.

Plumber Etobicoke Pro, a licensed plumbing company, advises, “You may need to flush your water heater more often if your water source is a well or if your city water has a higher sediment content than normal.”

Tools + Materials

  • garden hose
  • flat-head screwdriver

Turn Off the Water Supply

Firstly, turn off the water supply to your water heater. This is typically done by turning a valve on the cold-water inlet pipe near the tank’s top.

If you can’t find the valve, or if it’s frozen, you can shut off the water supply at the main valve for your home.

Turn Off the Water Heater

Once the water is turned off, you can turn off the water heater’s power. This is usually done by flipping a switch at the breaker box or unplugging the wall outlet heater.

Note: Electric water heaters must be completely off during flushing. Opened heating elements can quickly burn out if the water level in the tank drops below the level of the hot elements.

Most electric water heaters are connected directly to their circuit breaker. Locate the water heater circuit breaker in the main electrical panel.

“Even if the gas burner or electric heating elements are turned off, the water in the water heater tank can remain scalding hot for several hours.” 

Plumber Etobicoke Pro warns: “Either wait overnight for the water to cool before going to work, or use extreme caution and drain the scalding hot water away from areas where it could cause harm.”

Attach Hose to Drain Valve

Next, attach a garden hose to the drain valve on the bottom of the water heater. The other end of the hose must be placed in a large bucket or container to catch the water.

Please, locate the tank drain valve near the bottom of the tank and connect a standard garden hose to it. Remember that on some models, the opening of the valve may be covered by a cap. Place the other end of the hose in a drain hole in the floor or driveway where it can drain safely. Buckets can be used if necessary, but be careful not to burn yourself with hot water during operation.

Open Hot Water Tap

Open a hot water tap to allow air into the plumbing system. This will help to ensure that the water doesn’t flow back up the hose when you start draining the tank.

This step will relieve the pressure in the system, allowing water to quickly flow out of the tank, similar to how you remove your finger from the top of a straw filled with liquid.

Open Drain Valve

With the water turned off, you can open the drain valve to allow the water to flow out. Ensure you have a bucket or container ready to catch the water as it comes out.

When all the water is drained from the tank, briefly turn on the cold water supply to the tank. This will allow the remaining sediment to be agitated.

Repeat this process until the water is clear. Plumber Etobicoke Pro has seen some serious cases of sedimentation: “In some cases, sediment can block the drain valve opening, restricting water flow. In this case, it’s best to call in a professional for assistance.”

Close Valve, Refill Tank, Restart Water Heater

Close the drain valve. Remove the hose and turn on the cold water supply. The tank will begin to refill. Return to the hot water tap opened earlier. Once cold water starts flowing from the faucet, turn it off. Turn the gas valve on from the “pilot” position or reapply power to the tank. Be sure to check the valve opening after closing it to ensure there are no water leaks.

Warning: Some cylinders must be filled to avoid damage to the gas burner or heating elements. Always follow all manufacturer’s instructions and warnings for your particular water heater.