How to Fix a Noisy Water Heater: Common Causes and Troubleshooting Tips

Is your water heater making strange noises that keep you up at night? You’re not alone—and the good news is, you don’t have to live with it!

In this guide, we’ll show you how to fix a noisy water heater yourself. Whether it’s sediment buildup, a malfunctioning heating element, or something else entirely, the sounds like rumbling, ticking, pounding, hissing, clicking, or knocking typically have a straightforward cause—and an even easier solution.

Ready to silence the racket and restore peace to your home? Let’s get started!

How to Fix a Noisy Water Heater: The Most Common Signs

Water heater noise is typically caused by two main issues: water hammer and sediment buildup. However, there are also other reasons for strange sounds in your plumbing and water heating system.

It’s common to experience irritating noises from your water heater after a short period of use. Even if your heater is installed far from living spaces, like the bedroom or living room, you might still hear vibrations traveling through the plumbing. Some users report that the noise only occurs at night or in the morning—right after the unit turns on or following a shower.

In gas heaters, the noise can stem from droplets hitting crusty sediment formations, while electric units often produce a hissing sound due to limescale buildup on the heating elements.

If you’re wondering how to fix a noisy water heater, the first step is identifying the type of sound you’re hearing. Here are the most common water heater sounds you might encounter:

Pounding Noise in Water Heaters: Causes and Repair Tips

Why is my water heater making a pounding noise?

Mineral buildup and water hammer are the leading causes of the pounding noise your heater is making.

When water flows through the plumbing system and is suddenly stopped, a high-intensity shock wave travels through the pipes. This creates vibrations, resulting in pounding, banging, or thumping noises. These sounds, including knocking, are often linked to water hammer. To solve this issue, you can install a water hammer arrestor. For a step-by-step guide, check out our article on fixing water hammer.

Alternatively, the problem may stem from lime formations and sediment buildup at the bottom of the tank. To address this, professionals recommend installing a water softener or flushing the system periodically. For more details on troubleshooting sediment-related issues and noisy water heaters caused by limescale, refer to our article on sediments and lime build-up.

How to Fix a Water Heater Making Rumbling Noise

Aluminum hydroxide gel in the tank or plumbing is a major cause of rumbling noises in water heaters, often accompanied by mineral buildup. This gel forms due to a chemical reaction between the anode rod and water conditions, appearing as blue, green, or gray beads that accumulate in the heater drain or faucet aerators.

To address the problem, follow these steps:

• No lime buildup. If the water heater is new and has no lime build-up, turn off the heater, remove the anode rod, remove the anode rod, and flush the system thoroughly. Then reinstall the anode rod and turn the heater back on.
• For lime buildup. If there is lime buildup, use a recommended delimer (such as phosphoric acid or one recommended by the manufacturer) and follow the procedure for flushing the deposits.

Troubleshooting Water Heater Ticking Sound

The ticking noise in your water heater is often caused by pressure fluctuations within the piping system. If you have an energy-efficient unit, it likely includes heat traps. These heat traps contain a ball that can rattle inside the nipple due to temperature changes and the resulting expansion and contraction of materials, creating a ticking sound.

If the noise persists and no other solutions work, you can remove the heat traps. While this may slightly reduce energy efficiency, it won’t compromise the safety or operation of your heater.

Another possible cause of ticking is the plumbing pipes themselves. As hot water flows, pipes expand and contract, sometimes rubbing against loose straps or wood framing. To fix this, locate where the noise is loudest and secure the pipe or install plastic spacers to minimize movement.

A quick and easy way to reduce ticking is to lower the temperature on your water heater by just a few degrees. This small adjustment can often make a big difference.

Water Heater Makes Popping Noise (And Crackling)

The popping sound inside your water heater is typically caused by hard water and sediment buildup at the bottom of the tank and its components. These noises occur when water becomes trapped under mineral deposits and limescale. As steam bubbles form beneath the sediment, they eventually burst, creating popping or crackling sounds.

Limescale (CaCO3) is common in most home plumbing systems due to water hardness. Over time, especially with prolonged heating and high usage in areas with very hard water, limescale can accumulate significantly in the water heater.

To fix a noisy water heater, you can reduce water hardness by softening the water. One effective method is to flush the heater with an acidic compound, such as a delimer recommended by the manufacturer.

Additionally, a sudden stop in water flow can also cause popping or crackling noises. Another possible cause is condensation dripping onto the burner or other hot surfaces, which can produce similar sounds.

By addressing these issues, you can eliminate unwanted noises and keep your water heater running smoothly.

Sizzling Noise: What You Can Do to Repair It

The main reason for a sizzling sound in your gas water heater is a condensation or a leaking issue. This occurs when water droplets drip onto the flame, burner, or other hot surfaces.

Condensation forms when hot flue gases meet cooler surfaces inside the vent, creating water droplets. These drops then hit the hot surface every few seconds, producing the sizzling sound. You can observe this by checking the combustion chamber, where the flame will fluctuate between very bright and very dim.

It’s worth noting that some older units can produce up to half a gallon of water vapor per hour during operation. Typically, condensation stops once the entire heater heats up to temperatures above 115°F. However, if the issue is a leak, you’ll need to locate the source, tighten any loose fittings, or repair/replace the leaking component.

In some cases, a sizzling gas heater is normal. Natural gas contains high moisture content, which releases during combustion and can create these sounds.

For electric water heaters, sizzling noises often result from limescale buildup on the heating elements. Water trapped near the element boils, producing steam and the familiar sizzling sound.

How to Fix a Water Heater Hissing Noise

The hissing sound in electric water heaters is often caused by corroded heating elements. This occurs when water comes into contact with the electrically hot part of the element, creating the noise.

You may also hear this sound when the heating element is on and water trapped under limescale turns into steam. This is a clear sign that your water heater needs flushing, as the buildup reduces its efficiency.

Additionally, water heaters can produce a hissing noise when air escapes through the TPR (Temperature Pressure Relief) valve. Lowering the temperature can often eliminate this sound. However, if the hissing is accompanied by leaking, it’s a good idea to replace the TPR valve to ensure safe and proper operation.

Fixing Banging Noises in Your Water Heater

Banging noises from water heaters can sometimes come from the flue—the component that expels combustion gases to the outside. At the heart of the flue’s operation is the baffle, a metal device designed to slow airflow and improve the heater’s efficiency by maximizing heat transfer to the water. Over time, however, the baffle can loosen within its mounting bracket due to airflow and vibrations during operation. This causes metal-on-metal clanging as the baffle strikes the sides of the flue tube.

To fix this issue, you can adjust the baffle’s fit inside the flue. Start by tightening the baffle’s mounting bracket or bending the metal tabs on the hanger bracket for a more secure fit. Alternatively, you can remove the baffle, slightly bend it to improve its fit, and then reinstall it. These adjustments help secure the baffle, reducing noise while maintaining the heater’s performance and efficiency.

Water Heater is Humming

In electric water heaters, a humming noise usually stems from a loose heating element. These elements, located inside the tank, can vibrate when water flows past them if they aren’t securely tightened. Sediment buildup in the tank can amplify these vibrations, making the hum even louder.

Fortunately, the solution is straightforward: tightening the heating element and flushing the tank to remove sediment will often resolve the issue and eliminate the noise.

In gas water heaters, humming sounds are less common but can still occur. They’re typically caused by loose burner components or sediment buildup at the bottom of the tank. An unstable burner flame can also create vibrations if parts aren’t secure or if the tank base is uneven.

To fix this, start by securing the burner components and ensuring the tank is level. Then, flush the tank to remove any sediment. These steps should restore quiet operation and improve efficiency.

Conclusion

A water heater making unusual sounds isn’t dangerous, but it’s a clear sign that regular maintenance may have been overlooked. It could mean the unit needs servicing or that one of its components is failing and requires replacement.

By following the steps outlined in this guide on how to fix a noisy water heater, you can address these problems effectively and restore peace to your home. Regular maintenance, such as flushing the tank and checking for loose parts, can also prevent future noises and keep your water heater running smoothly. If the issue persists, don’t hesitate to consult a professional for further assistance.