Home Improvement Ideas Plumbing Installations & Repairs How to Flush a Water Heater Flush built-up mineral scaling, sediment and debris out of your water heater. By Timothy Dale Published on November 20, 2023 Trending Videos Close this video player Photo: Tim Abramowitz Project Overview Working Time: 45 minutes Total Time: 1 hour, 30 minutes Skill Level: Intermediate Estimated Cost: $0 to $50 Water heaters are responsible for rapidly heating incoming cold water and routing the newly heated water to various faucets, showers, tubs, and water-using appliances throughout the home. Without one, your dishwasher and washing machine can't function properly and residents can’t take a hot shower or wash their hands in warm water. Keeping up with routine maintenance, including flushing the water heater, is necessary to keep a water heater working properly. It should be flushed about once a year to remove mineral scaling, sediment buildup, and other debris. Use this guide to learn how to flush a water heater. The 9 Best Tankless Water Heaters of 2024 Signs a Water Heater Needs to Be Flushed In general, it’s a good idea to flush the water heater about once a year. Additionally, if the water heater starts showing signs of a problem, you might need to flush the tank to resolve the issue. If sediment and mineral scaling build up in the water heater, they can prevent the element from heating the water, leading to low heating efficiency, lukewarm water, and high energy bills. In some cases, you can see the sediment in the water, which indicates the water heater needs to be flushed. Other signs include a rotten egg smell from the water, odd noises from the water heater, rust-colored water, and low water pressure. Flush the water heater to fix the problem. If this doesn’t work, contact a professional plumber to assess the issue and make repairs. Safety Considerations Burns are the biggest risk when flushing a water heater. The water inside the tank is incredibly hot, so turn off the water heater the night before starting this project to give the water in the tank time to cool down, reducing the risk of being burned. Cool water is also useful for watering the garden or the lawn instead of draining the tank into the sewer. There is a risk of flooding the home if the connections are not secure. Take your time to inspect and properly attach the garden hose to the drain valve, and then run the garden hose to a safe drainage location. After opening the drain valve, inspect the entire length of the hose for leaks. If you spot any leaks, close the drain valve and replace the garden hose with a new hose before proceeding with this job. What You'll Need Equipment / Tools Channellock pliers Materials Garden hose Bucket Towels Instructions How to Flush a Water Heater Turn Off the Power Water heaters use electricity, natural gas, or propane to heat a large amount of water. Turn off the water heater the night before to give the water inside the tank enough time to cool down. Turn off the electricity to the water heater by switching off the corresponding breaker in the breaker box. If you have a gas or propane water heater, locate the thermostat on the outside of the water heater and turn it to the lowest setting. You should not have to turn off the natural gas or propane supply valves for this process. Setting the thermostat to the lowest level will ensure the appliance is not heating. How to Shut Off Water Close the Water Supply Valve If you can’t leave the water heater off overnight, another option to handle hot water is to open a nearby faucet or shower to allow the hot water to drain and be replaced with cold water. When most of the hot water has been used and replaced with cold water, turn off the water supply valve. It should be located on the top of the water heater where the cold water pipe enters the tank. Connect a Garden Hose to the Drain Valve The water heater has a drain valve that is typically located at the base of the tank. Find the drain valve and connect the garden hose to the drain valve. Tighten the connection with a set of Channellock pliers to ensure it will not leak. Run the other end of the hose to an area where the tank can safely drain—a lawn, garden, or nearby sewer. Make sure the force, temperature, or amount of water won't damage the location. Open the Drain Valve to Drain the Water Open the drain valve to begin draining the water from the water heater. A vacuum can be created in the water system when draining the water heater, so to avoid this issue, open a nearby hot water faucet. If necessary, open the pressure relief valve to improve the flow of water through the drain, although you need to place a bucket under the discharge pipe to catch any water that runs out of this valve. Test the Water Contents The purpose of flushing the water heater is to remove any built-up sediment, debris, or mineral scaling. After allowing the tank to drain for 10 to 20 minutes, fill up a bucket with water from the garden hose and let it sit undisturbed for a minute. Check the bucket to see if the water is clear and if there is any sediment or debris in the bottom of the bucket. If the water is cloudy or sediment is present, you need to keep draining the tank. You can test the water contents in this way about once every 10 minutes until the water is clear and sediment-free. Close the Drain Valve When the water looks clean, close the drain valve and remove the garden hose. To avoid spilling water everywhere, keep the end of the hose directed up until it is outside or over a drain. Also, keep the nearby hot water faucet open to bleed air from the water line. Restore the Water and Power Open the water supply valve and let the water heater fill up. As the tank fills with water, the air trapped in the tank is gradually forced out through the open faucet. You can also open the pressure relief valve to release air from the tank. Wait until the water heater is full before turning on the breaker switch to restore power to the appliance. Make sure to turn the thermostat back up to the original setting. Then, close the faucet and pressure relief valve. The water should take about 20 to 30 minutes to heat up. After waiting a half hour, open a nearby faucet to test the water temperature and verify that the job was completed successfully. All the Pros and Cons You Need to Know About Tankless Water Heaters When to Call a Professional DIYers who don’t have experience working with plumbing systems should not attempt this project on their own. They need to have an experienced DIYer nearby to help with the job. If this isn’t possible, it’s best to leave this maintenance task to a trained professional. Similarly, if you encounter any problems, such as the drain valve won’t open or the water never seems to run clean, then you should contact a professional plumber to assess the situation and make necessary repairs. In some cases, the water heater is too old or has been left for too long without proper maintenance, leading to internal damages that cannot be repaired. If this occurs, the plumber will likely suggest replacing the water heater entirely.