Why Is My Water Heater Making Noise?

Popping and rumbling from sediment

The most common water heater noise is a popping or rumbling sound that happens when the burner or electric element heats the tank. That sound is caused by sediment — mostly calcium and magnesium minerals from hard water — collecting at the bottom of the tank. Water trapped under the sediment bubbles and pops as it is heated.

Over time, sediment acts like an insulating blanket between the burner and the water. The bottom of the tank overheats, which stresses the glass lining and steel. The tank has to run longer and hotter to deliver the same amount of hot water, which raises energy bills and shortens the unit's life.

Flushing the tank removes most loose sediment. The process involves attaching a hose to the drain valve, letting water run out until it is clear, and refilling the tank. If the drain valve is clogged with sediment or the tank has not been flushed in years, a professional should handle it. Forcing a clogged valve can break it and cause a leak.

Whining or screeching from valves and elements

A high-pitched whining or screeching sound often comes from a partially closed water valve or a restricted flow path. Check the shut-off valve near the water heater and make sure it is fully open. If the valve is a gate valve, the internal gate may have broken off and partially blocked the pipe.

In electric water heaters, a whining noise can also come from a failing heating element. As scale builds up on the element, it heats unevenly and can make a humming or whining sound. A cracked or burned-out element may continue to work for a while, but it will fail eventually. Replacing the element is usually straightforward for a professional.

Ticking and tapping from heat expansion

Ticking or tapping sounds are usually caused by heat expansion. As hot water runs through the pipes, the metal expands and rubs against framing, straps, or wall studs. The sound may seem to come from the water heater, but it is often in the pipes nearby.

Expansion can also cause pressure spikes inside the tank. Most tanks have a temperature and pressure relief valve that releases a small amount of water if pressure gets too high. If you hear the relief valve opening frequently, or if you see water discharging from the pipe, the pressure in the system may be too high. This can happen because of a closed system, a failed expansion tank, or a water pressure regulator set too high.

When noise means replacement is near

Noise alone does not always mean a water heater needs to be replaced. Sediment can often be flushed. Valves can be opened or replaced. Elements can be swapped. But there are times when noise signals the end of the unit's useful life.

If the tank is more than ten years old, rumbling often means the bottom is heavily coated with sediment and the lining may already be damaged. If you see rust-colored water, moisture around the base, or a leaking temperature and pressure relief valve, replacement is usually the smarter choice. Continuing to run a failing tank risks a sudden leak and water damage.

Prevention and regular maintenance

The best way to avoid noisy water heaters is annual flushing, especially in areas with hard water. Draining a few gallons from the tank every six months can prevent heavy sediment buildup. Keeping the thermostat at 120°F reduces stress on the tank and lowers energy use.

If your home has very hard water, consider a scale-reduction system or water softener. These systems reduce the minerals that cause sediment and extend the life of the water heater, faucets, and appliances. A plumber can test your water hardness and recommend the right solution for your home.