Water Heater Making Noise? Popping, Rumbling and What to Do

Quick answer: Popping and rumbling from a water heater usually mean sediment at the bottom of the tank. Hissing or sizzling can mean water is dripping on a hot burner or scale on an electric element. Ticking is usually pipes expanding. Knocking may be water hammer. Flushing can help when sediment is the cause, but very old tanks may be better replaced. Noise with a leak, dripping relief valve, gas smell or CO alarm needs quick attention. Book water heater repair for an honest assessment.

Water heaters should be fairly quiet. If yours has started popping like a coffee percolator or rumbling in the basement, it's telling you something about what's going on inside. Here's how to translate the sounds.

What each sound means

Popping and rumbling: sediment

Minerals in your water settle at the bottom of a tank. On gas heaters, this layer sits between the burner and the water. Water trapped below it overheats and bursts through in small steam bubbles, which causes the pop. Over time this can:

• Waste energy, because heat has to travel through the sediment
• Slow recovery, so hot water runs short
• Overheat the tank bottom, which can shorten its life
• Clog the drain valve and damage electric elements

Hard water and well water make it worse. Homes on wells, which are common in rural parts of our service area, should keep a closer eye on this. See flushing a water heater and hot water runs out fast.

Hissing or sizzling

On a gas heater, hissing or sizzling often means water is hitting the hot burner. It could be simple condensation, especially when very cold water fills a tank in winter. It could also be a leak, which is more serious. Check for moisture at the base and the burner area.

On an electric heater, sizzling usually means scale has built up on an element. The element can burn out as a result.

If you hear hissing at a valve or a pipe, check the relief valve discharge pipe. Water discharging there can mean high temperature or pressure. Never cap or plug a relief valve.

Ticking and tapping

Metal pipes grow slightly as they warm up and shrink as they cool. Heat trap nipples at the top of the tank can also tick. This is usually harmless. If it's annoying, ask about pipe strapping or changes to the heat traps.

Knocking and water hammer

Water hammer is the bang you may hear when a faucet, washer or dishwasher valve closes quickly. It isn't caused by the water heater, but you can hear it near the tank, because pipes transmit sound. An arrestor or an expansion tank can help, and high water pressure is worth checking.

Screeching or whistling

This can mean water is being forced through a partly closed valve, or that steam and hot water are escaping somewhere they shouldn't. Check that the cold water supply valve is fully open. If the sound comes from the relief valve, call for service right away.

Tankless water heater noises

Tankless units make different sounds. Fan noise and clicking at ignition are normal. Watch for:

• Loud rattling: a failing fan or loose parts
• Rumbling or kettling: scale inside the heat exchanger
• Repeated clicking with no hot water: ignition failure
• Error codes: note them for the technician

See descaling a tankless water heater.

What to do right now

1. Listen for where the sound comes from: tank, burner, valve or pipes.
2. Check the base for moisture and the relief valve pipe for drips.
3. Check the temperature setting. Around 120°F suits most homes.
4. Look for rusty water coming out of hot taps.
5. Record a short video, because noises tend to stop as soon as the technician arrives.
6. Note the age from the label or serial number.

Don't open gas controls or electrical panels, and be careful about flushing a very old tank yourself.

When to act right away

• Gas smell: leave the house and call 911 or your gas utility from outside
• Carbon monoxide alarm: get everyone outside and call 911. See carbon monoxide safety.
• Relief valve discharging hot water
• Water pooling around the tank. See water heater leaking: what to do.
• A yellow, sooty flame on a gas heater

To stop a leak, close the cold water valve above the tank and turn off gas or power to the heater.

Will flushing fix it?

Flushing a neglected tank can stir up sediment that clogs the drain valve or exposes a weak spot. It's fine to ask for a professional opinion first.

Repair or replace?

Consider replacing when:

• The tank is around 8 to 12 years old or older
• The noise comes with rusty water, leaks or slow recovery
• Flushing no longer helps
• Repairs are adding up

See water heater lifespan, what's included in a replacement and tankless vs tank. For prices, see what affects water heater repair cost.

How to keep your heater quiet

• Flush tanks as your manufacturer recommends
• Descale tankless units on schedule
• Consider water treatment if you have hard water or a well
• Keep the temperature moderate: hotter water speeds up scale
• Have the anode rod checked on tanks you want to keep
• Check water pressure if you often hear banging

What noise means for your energy bills

Sediment doesn't just make a racket. It sits between the burner and the water on gas heaters, so more fuel is needed to deliver the same hot water. On electric heaters, it can bury the lower element and shorten its life. If your bills have crept up while hot water has started running short, sediment may be behind both problems.

Noise is also one of the earlier warnings you'll get. A tank that has started popping or rumbling often has time left, which means you can plan a flush or a replacement instead of dealing with water on the floor at the worst possible moment.

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Same day water heater service near you

We repair and replace gas and electric tank water heaters and tankless units of every brand across all 153 towns in Ocean, Monmouth, Burlington and Middlesex counties. That includes Brick, Middletown, South Brunswick and Cinnaminson.

Noisy water heater? Book online or call (732) 779-7106 for same day service and an upfront price.