How to Flush a Water Heater to Stop Popping Noises
About This Project
A comprehensive guide to flushing a water heater tank to remove sediment buildup. This process involves shutting off the power and water supply, draining the tank, using cold water pressure to flush out accumulated minerals, and then safely refilling and restarting the unit. This maintenance procedure is the primary method for resolving popping or rumbling noises caused by trapped water boiling beneath a layer of sediment.
Best for homeowners and DIY enthusiasts with basic plumbing knowledge. Requires Voltage / Circuit Tester and Element MAXLite 5/8 in. dia x 25 ft. Hot Water Rubber+ Hose CELHW58025DA and Panther Vision FLATEYE F-310 High Performance 310-Lumen Unround Flashlight CREE LED Multi Position Waterproof and Shockproof FL-6960.
Tools & Materials
Voltage / Circuit Tester
Work Gloves
Wrench
GardenJoy PVC Garden Hose 5/8 in. x 75 ft. Heavy-Duty Durable Hose Outdoor Water Hose LG-GHB5875
Safety Glasses
MCR Safety BearKat Safety Glasses MCSCRWBK110
Voltage / Circuit Tester
Detects electrical voltage presence.
Work Gloves
Protects hands during tasks.
Wrench
Turns objects with grip and leverage.
GardenJoy PVC Garden Hose 5/8 in. x 75 ft. Heavy-Duty Durable Hose Outdoor Water Hose LG-GHB5875
Light-weight and Flexible: Made from premium PVC, our garden hose is both light-weight and durable, allowing for easy handling without kinks or tangles, ideal for all your watering and cleaning needs.
Safety Glasses
Keeps eyes safe from potential hazards.
MCR Safety BearKat Safety Glasses MCSCRWBK110
Safety glasses feature a well thought-out construction that combines the best in safety, comfort and affordability. Your vision is unobstructed by the 1-piece wraparound lens which, by its tight fit, provides for maximum safety. Flexible temples enhance your comfort during extended use. Nonslip rubber head grips are notched for a clip-on breakaway cord.
Steps
Shut Off Power Supply
5 minsBefore starting any work, ensure the power supply to the electric water heater is completely cut off. Locate your home's main electrical panel (breaker box). Find the breaker labeled 'Water Heater'—it is typically a double-pole breaker (two switches connected together). Firmly switch it to the 'OFF' position. For added safety, you can use a voltage tester at the heater's electrical connection point to confirm the power is off. For a gas heater, you would locate the gas control knob on the front of the unit and turn it from 'ON' to the 'PILOT' or 'OFF' position.
Turn Off the Cold Water Supply
5 minsLocate the cold water supply pipe entering the top of your water heater; it is often marked with a blue ring or handle. Find the shut-off valve on this pipe, which will either be a wheel-style gate valve or a lever-style ball valve. Turn the wheel-style valve clockwise until it stops. For a lever-style valve, turn it a quarter-turn so the handle is perpendicular to the pipe. This stops new water from entering the tank as you drain it.
Connect Drain Hose
5 minsAttach one end of a standard garden hose to the drain valve located near the bottom of the water heater tank. The valve will have a threaded, hose-bibb style connection. Ensure the connection is hand-tight to prevent leaks. Place the other end of the hose in a safe drainage area that can withstand hot water, such as a basement floor drain or a bathtub. Make sure the hose end is lower than the bottom of the tank to allow gravity to drain the water effectively.
Open a Hot Water Faucet and T&P Valve
5 minsTo prevent a vacuum from forming inside the tank, which would slow or stop the draining process, open a hot water faucet in your home. The faucet in a nearby utility sink, kitchen sink, or bathtub is ideal. You will hear air being drawn into the faucet as the water level in the tank drops. Additionally, it is wise to open the temperature and pressure relief (T&P) valve on the side or top of the tank by lifting its lever. This will also help introduce air and speed up draining.
Open Drain Valve and Drain Tank
20 minsUsing channel-lock pliers or a flathead screwdriver (depending on the valve type), carefully turn the drain valve handle or slot counter-clockwise to open it. Water will begin to flow through the hose. The initial flow may be slow if sediment is already blocking the valve opening. Allow the tank to drain completely. This can take anywhere from 15 to 45 minutes depending on the size of your tank.
Flush Out Sediment
15 minsThis is the most critical step for eliminating the popping noise. With the drain valve still open and the hose in place, turn the cold water supply valve on for 15-30 seconds. This will send a blast of cold water into the bottom of the tank, stirring up the heavy sediment. Then, turn the cold water off and let the water and sediment drain out. Repeat this process 4-5 times, or until the water draining from the hose runs clear. This action breaks up the mineral deposits that cause the popping sounds.
Close Valves and Refill the Tank
10 minsOnce the water runs clear, close the tank's drain valve securely by turning it clockwise. Then, close the T&P valve if you opened it. Disconnect the garden hose from the drain valve. Finally, go to the cold water inlet valve and turn it back on (counter-clockwise for a wheel, parallel to the pipe for a lever). You will hear the tank begin to fill with water.
Purge Air From the System
10 minsLeave the hot water faucet (that you opened earlier) running while the tank refills. At first, it will spit and sputter as air is pushed out of the tank and pipes. Once a full, steady stream of water is flowing from the faucet, all the air has been purged from the system. At this point, you can turn off that faucet. Check for any leaks around the drain valve and T&P valve on the heater.
Restore Power
5 minsWith the tank completely full of water and all air purged, you can now safely restore power. Return to the electrical panel and flip the water heater's breaker back to the 'ON' position. The water heater will now begin to heat the new water. It will take 1-2 hours for the water to become fully hot again. For a gas heater, you would turn the gas control knob back to 'ON' and follow the manufacturer's instructions for relighting the pilot light, if necessary.
Common Problems
Gas leaks can be dangerous. If you smell gas, do not attempt this repair and contact a qualified technician.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
Can't find the water shut-off valve.
Solution: On a traditional water heater, the shut-off is usually a valve on the cold water pipe at the top of the tank. On a tankless heater, it will be one of the valves directly underneath the unit.
No dedicated shut-off valves mean you can't isolate the water heater.
Solution: If your water heater doesn't have dedicated shut-off valves, you will need to turn off the main water supply to the house.
Sudden water surges can cause water hammer and damage your system.
Solution: Slowly turning on the water prevents a sudden surge of pressure (water hammer) that could damage the system.
Do not turn the power back on until the tank is completely full of water.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
Open the valves slowly to prevent water hammer, which can damage your plumbing.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
It is critical to ensure the tank is completely full before restoring power to prevent destroying the new element.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
Frequently Asked Questions
Why is my water heater making popping or rumbling noises, and how does flushing fix it?
Popping or rumbling noises are typically caused by sediment (like calcium, magnesium, or rust) accumulating at the bottom of your water heater tank. Water trapped beneath this layer gets superheated and boils, creating steam bubbles that cause the popping sounds as they escape. Flushing removes this sediment, allowing the heating element to heat water directly and quietly.
What essential safety gear and tools do I need before starting this project?
For safety, ensure you have safety glasses (e.g., HDX Clear Indoor Safety Glasses), heat-resistant gloves (Dyna-Glo Grilling Glove), and general work gloves. Key tools include a heavy-duty garden hose (like GardenJoy PVC Garden Hose) for draining, Channellock Tongue and Groove Pliers for valve adjustments, and a Milwaukee Slotted Flat Head Screwdriver.
How long will this project take, and how difficult is it for a beginner?
For a beginner, this project typically takes 1-2 hours to complete, including the shutdown, draining, flushing, refilling, and restart process. It's considered a beginner-level DIY task, but requires careful attention to each step to ensure all sediment is removed and the system is safely restarted without issues.
What are some common mistakes to avoid when flushing my water heater?
A common mistake is not fully shutting off both the power and the cold water supply to the tank before beginning the drain. Also, ensure your drain hose is securely connected to prevent leaks and water damage. After refilling, always remember to purge all air from the system by opening a hot water faucet to prevent airlocks.
What should I do if the popping noises persist even after I've flushed the water heater thoroughly?
If popping noises continue, it might indicate that some stubborn sediment remains, or there could be a more significant issue like a failing heating element or internal tank problem. You can try a second, more thorough flush, allowing cold water to agitate the tank longer. If the problem persists, it's advisable to consult a professional plumber for further diagnosis.
Do I need any special solutions or chemicals to clean out the sediment, or is just water enough?
No, special solutions or chemicals are generally not recommended or necessary for a routine water heater flush. The flushing process relies solely on the force of cold water entering the tank to agitate and expel the accumulated sediment through the drain valve. Using harsh chemicals could potentially damage the tank's interior lining or leave harmful residues.