Why Is My Water Heater Making Noise? What Each Sound Means

Most water heater noises come from sediment at the bottom of the tank. Minerals in your water settle and form a layer over time. Water gets trapped under that layer, heats up, and bursts through with popping and rumbling sounds. Flushing the tank once a year usually stops it.

Other sounds, like ticking, humming, or screeching, have different causes. Some are harmless, while a few mean you should call a plumber.

This guide helps you match the sound you hear to its cause, explains how to flush your tank step by step, and tells you when a noise is a warning sign.

What does each water heater sound mean?

Popping and rumbling: sediment buildup

This is the most common water heater noise. Tap water has minerals like calcium and magnesium in it. When water heats up, these minerals settle at the bottom of the tank. Over the years, they build a hard, crusty layer.

Water gets trapped under the sediment. When the burner or element heats it, the water turns to steam and pushes up through the layer with a pop. Lots of pops together sound like rumbling or even boiling.

Sediment is not just noisy. The Department of Energy notes that it makes your water heater work harder, which wastes energy and can shorten the life of the tank.

Homes with hard water get sediment faster. If you see white crust on your faucets and shower heads, you likely have hard water.

Fix: Flush the tank. The steps are below.

Crackling and sizzling

On an electric water heater, crackling often means sediment has covered the heating element inside the tank. Flushing the tank helps.

On a gas water heater, a soft sizzle can happen when a little water drips onto the hot burner. This is often condensation, and it is normal when the tank is filling with cold water. But if the sizzling does not stop, check the tank and pipes for leaks.

Ticking and tapping

Metal pipes grow a tiny bit when hot water flows through them and shrink as they cool. This can make a ticking or tapping sound. Some water heaters also have small heat trap valves on the pipes at the top, which can tick.

Fix: This is usually harmless. If the noise bothers you, a plumber can add pipe straps with padding or swap the heat traps.

Humming

Electric water heaters can hum when cold water flows over the heating element and makes it vibrate. A loose element can make the hum louder.

Fix: A plumber or handy homeowner can tighten the element. Always turn off the power at the breaker before opening any panel on an electric water heater.

Screeching or whistling

A high-pitched screech usually means water is being squeezed through a small opening. A valve that is only partly open is a common cause.

Fix: Check that the cold water inlet valve at the top of the tank is fully open. If the sound comes from the temperature and pressure relief valve (the valve with a lever, usually on the side or top of the tank), see the next section.

Hissing from the relief valve: take this one seriously

The temperature and pressure relief valve, often called the T&P valve, is a safety part. It opens to let out water or steam if the tank gets too hot or the pressure gets too high.

If this valve is hissing, dripping, or letting out water, something may be wrong with the temperature setting, the water pressure, or the valve itself.

What to do:

1. Turn off the water heater. Set a gas heater to "off" or "pilot." Turn off the breaker for an electric heater.
2. Do not cap, plug, or remove the valve.
3. Call a licensed plumber.

Banging: water hammer

A loud bang in the pipes right after a faucet, washing machine, or dishwasher shuts off is called water hammer. The water is moving fast, stops suddenly, and slams into the valve.

Fix: A plumber can add a small part called a water hammer arrestor. High water pressure can make water hammer worse. Our guide on home water pressure explains what normal pressure looks like.

How to flush a tank water heater

Flushing removes sediment and quiets most popping sounds. It takes about 1 to 2 hours. Always check your owner's manual first, since steps can vary.

You will need: a garden hose, a bucket, and gloves.

1. Turn off the heat. For a gas heater, turn the control knob to "pilot" or "vacation." For an electric heater, turn off the breaker.
2. Turn off the cold water supply. Close the valve on the cold water pipe at the top of the tank.
3. Let the water cool. Wait a few hours if you can. Tank water can be hot enough to burn you.
4. Attach a hose. Connect a garden hose to the drain valve near the bottom of the tank. Run the other end to a floor drain, a bucket, or outside, lower than the drain valve.
5. Open a hot water faucet somewhere in the house. This lets air in so the tank can drain.
6. Open the drain valve. Let the tank empty. You may see cloudy water and bits of sediment.
7. Flush it out. When the tank is empty, turn the cold water supply on for a few minutes to stir up and wash out more sediment. Repeat until the water runs clear.
8. Close the drain valve and remove the hose.
9. Refill the tank. Turn the cold water supply back on. Leave the hot faucet open until water flows out of it smoothly with no sputtering. This means the tank is full.
10. Turn the heat back on. Relight or turn the gas heater back to its setting, or turn the breaker back on for an electric heater.

Important: Never turn on an electric water heater while the tank is empty. The elements can burn out in seconds.

If only a little sediment comes out and the popping continues, the sediment may have hardened. A plumber can use stronger methods, or it may be a sign that the tank is near the end of its life.

Other ways to prevent noise

• Flush once a year, or every 6 months with hard water.
• Check the anode rod every few years. This metal rod helps protect the tank from rust. When it wears out, the tank can start to rust from the inside. A worn anode rod can also make hot water smell like rotten eggs. Learn more in our guide on sulfur smells in tap water.
• Set the temperature to about 120°F. The Department of Energy suggests 120°F for most homes. It saves energy and lowers the risk of burns.
• Think about a water softener if you have very hard water.

When it is time for a new water heater

A tank water heater usually lasts about 8 to 12 years. Think about replacing yours if:

• It is more than 10 years old and very noisy even after flushing
• You see rust on the tank or in your hot water
• The tank is leaking from the bottom
• You run out of hot water much faster than before

You can find the age on the label. The serial number often includes the year it was made.

The bottom line

Popping and rumbling are almost always caused by sediment, and a yearly flush usually fixes them. Ticking and light sizzling are often normal. But hissing from the relief valve, leaks, or loud banging from the tank are signs to turn off the heater and call a plumber. A little yearly care keeps your water heater quiet and helps it last for years.