Water heater being flushed (C) Daniel Friedman Hot Water Heater Noise FAQs

  • WATER HEATER NOISE FAQs - CONTENTS: Water heater noise questions & answers: what causes noisy water heaters, calorifiers, geysers? Some of these noises indicate danger and some probably not.
  • POST a QUESTION or READ FAQs about water heater noise troubleshooting and water heater scale and lime removal
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Water heater noise questions & anwers: FAQs:

Questions, answers & solutions for water heater noises, bangs, hisses, gurgles, rumbles Calorifier noise, Geyser noise. This article lists frequently asked questions about water heater noises & sounds and includes answers to common water heater noise complaints or worries.

This article series explains how to diagnose and cure noisy water heaters such as popping, hissing, crackling or banging. We describe the different types of sounds heard at a water heater, what they mean, their cause, and their elimination. The sketch at page top is courtesy of Carson Dunlop Associates.

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Noise Diagnosis & Repair FAQs for Residential Hot Water Heaters

Measuring thickness of scale in water heater tank bottom (C) Daniel Friedman

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Questions and answers about water heater noise diagnosis and cure posted originally at WATER HEATER NOISE - topic home.

On 2017-05-24 by (mod) re: curing a humming noise at a water heater

Thanks for the great question, Ronald.

At WATER HEATER NOISE we describe several causes of humming sounds at water heaters, calorifiers, geysers or cylinders - the term depends on where you live. The most-common cause of humming water heaters on electric models is a vibration at the heating element caused by water turbulence. Here's what to do:

Humming sounds from an electric water heater can be caused by turbulence in water inside the heater as water flows around its one or two electric heating elements. Some heater experts suggest trying to slightly tighten the electric heater element in its mount to stop or reduce its vibration. By turning the (loop-shaped) electric heater element in position inside the heater you are changing the direction of water flow across that element as water enters and leaves the heater.

That may stop the noise. If it is impossible to rotate the heating element clockwise (rightie-tightie) you can still make an adjustment by loosening the element - turning it counterclockwise. But watch out for leaks. If leaks start you'll need to drain the heater, remove the element, apply new teflon paste or tape to the treads, and position it anew in its mount. At that point, just tighten the element enough that it's secure and not leaking (on re-fill of the heater). Then if the noise is absent, stop there. If the noise is present you'll be able to rotate the element 1/8 of a turn at a time until the noise stops.

Watch out: never turn an electric water heater back ON before making sure that all of the air has been removed from the tank or the element will burn up immediately.

If that has no effect, I'd also try slightly closing the control valve on the heater's cold water inlet side to see if slowing the water flow rate/volume has an effect.

Check those two points and let me know if that works for you, as what you find will help other readers.

On 2017-05-24 by Ronald W T Bull

There appears to be a low humming sound comming from the hot water system

On 2017-05-23 by (mod) re: water heater knocking, banging, rumbling, clunking, gurgling, popping or thumping noises and scale deposits

Typically, Charles, the problem you describe is caused by water heater scale mineral deposits. You can see live links to recommended cures in the article above near its end in the section titled "Cures for Hard Water that Clogs Hot Water Tanks, Tankless Coils, and Plumbing Pipes" or you can Use the search box just above to find our article series on WATER HEATER SCALE REMOVAL.

On 2017-05-23 Charles Brinker

water heater keeping a knocking noise when heating. What would cause that?

On 2017-05-21 by (mod) re: noise from a hot water circulating pump


Discuss with your plumber the use of sound isolating plumbing support fittings, as often noise or pump vibration is being transmitted via plumbing piping. Also ask if the pump is working normally - the sound could indicate a failing bearing or other component.

On 2017-05-21 by Anonymous

hot water heater pumping noise keeps me awake in a big apartment

On 2017-05-06 by (mod)


Check out WATER HEATER SCALE DE-LIMING PROCEDURE where we show the Bold font titled continue reading at. Because most likely the sound that you describe is due to scale formation inside of your water heater.

Or you can use the InspectApedia search box on any of our pages to search this website for

WAYER HEATER SCALE to see all of our articles on that topic

On 2017-05-04 by Melody

Our 8 mo old gas water heater was making a loud rumbling noise that sounded like an idling large big rig truck, vibrated through the garage and could be heard through the house.

The noise lasted for 30 - 40 seconds and came intermittently many times a day for about 5 days until it stopped and the water heater will now only barely keep the water slightly above cold. This is not a type of noise I saw listed and am confused by it. It sounded as if it was a motor noise and we didn't realize it was the water heater until it died.

On 2017-02-02 by Louise M.

My water heater makes gurggling and popping and popping noises when we turn on the hot water.

On 2017-05-06 by (mod) re: how to fix a screaming water heater

David, see see WATER HEATER WHISTLE NOISE - screaming tankless water heater diagnosis

On 2017-01-02 by David Birgin - screaming water heater

My hot water system makes screaming noises when we turn on the hot water
How do I fix this please

On 2017-05-06 by (mod) re: how to fix air noises in water heaters

Nancy and LW:

if there is air in the water heater tank or pipes AND if you previously purged air from the system by running hot water at a nearby tap, there may be an air source into your water system, especially if you're on a private well.

Please use the InspectApedia search box to find our article on AIR DISCHARGE AT FIXTURES to see details of the causes and cures of this problem.

On 2016-12-14 by Nancy

What makes it sound like air is in the tank or pipes when you turn the hot water on.

On 2016-11-30 by LW re: bubbling slushing sounds in water heater

My electric water heater is on a timer and heats for a few hours in the middle of the night. When it initially starts heating it makes an incredibly loud bubbling/rushing sound that actually sounds like a toilet being flushed.

Last week it made popping and gurgling sounds and cold water wouldn't come out of one tap in the house - only boiling hot water came out (other taps weren't impacted). The plumber who came by the next day had no idea what could be happening. Any ideas? Thank you!

On 2016-11-03 by Jenny

I am living in condo. There are two pumps running chiller or boiler. When one of the pumps are on, my unit can hear loud vibration humming noises. What puzzles me is only my unit can hear this noise. Last several days when two pumps were running, the noise level was acceptable but early this morning at 3:42, the very loud noises started and are there all the time. This happens when running the chiller as well. Can you please tell me what possible reasons are. The noises are so annoying but the building has to run two pumps. Thanks.

On 2016-09-19 by Anonymous

can you use a higher wattage element from 4500 to 5500 wats

On 2016-08-21 by (mod)

I don't know what the humming is, Az.

On a few water heater models, particularly those using a rather long heating element, water flowing across the element may cause it to vibrate and may generate a humming sound.
You can probably diagnose this cause of humming electric water heater noise by turning off water into the heater or by making sure that nobody in the building is running hot water. If no water is running through the heater and the noise stops, you've found the probable cause.

If the humming IS traced to the heating element, ask your installer to inspect the element installation; simply tightening it may stop the humming noise.

Watch out: left-unattended, a humming vibrating electric water heater element might begin to leak at its mount.

Is there a circulator on your water heating system? If so check the pump for noise.

Watch out: a failing or mis-wired electrical circuit could cause buzzing or humming - that would be unsafe.

Are you sure it's really humming and not rumbling or hissing -sounds associated with scale deposits or simply with water heating up>?

Try turning power to the heater off, wait 5 minutes, then turn it on. Let me know what you observe.

Finally: a new heater and its installation should be under warranty so it makes sense to call the installer for help.

On 2016-08-21 by Azcabin

Our new electric water heater (3 months old) is making a very loud high pitched humming noise, any idea why?

Question: My 8 year old water heater is making a noise

Thank you for this article. I'm hearing a noise from the water heater, that should be it. 8 years old! - Frank 8/16/11


Glad to help, Frank, let us know what you find - doubtless it will help other readers. And we welcome questions or content suggestions about articles found at InspectAPedia. Dan

Question: Does mineral buildup inside a water heater cause the resulting hot water to be even harder due to dissolved minerals?

Does mineral buildup inside a water heater cause the resulting hot water to be even harder due to dissolved minerals? I have noticed problems with difficult to remove scale in my shower and, more importantly, my hair will not behave!!! (seriously) It is a 40 gallon tank, and as a single person who does very little laundry (uniforms are laundered and provided by employer)and doesn't run the dishwasher often, I'm wonderng if I simply don't turn that 40 gallons over quickly enough? Perhaps an on-demand heater would be better for me? Thank you for the article. - Judy 9/13/11


A short answer to the question - does an existing mineral deposit in a water heater make water evev harder, its possible but unlikely. Mineral deposits in a heater form as incoming water, bearing dissolved minerals, is heated, speeding precipitation of mineral salts.

Consider a heating boiler, not a water heater for a point of comparison. In a heating boiler the same physical quantity of water that entered the boiler remains therein - it is not consumed and little or no new water enters the system. In that case the amount of mineral salts available to form a precipitate or deposit is fixed, and small. And we do not normally see a problem with mineral deposits in heating boilers as a result.

In contrast, still using home heating boilers, a steam boiler does consume water qt every heating cycle, and as new water enters that boiler constantly, the available mineral molecules to be deposited and accumulated inside the boiler can be significant, especially when the water supply is high in mineral content.

A home water heater in active use is operating like a steam boiler when occupants are using up hot water. When no one is using any hot water, no new cold water enters the tank, so no mineral deposition stops.

Your question asks if we see the opposite reaction, dissolving minerals back out into the static water in the heater. I doubt that there is a significant back reaction - we don't see mineral deposits easily dissolving back into the water as er do not see water scale deposits disappearing on their own.

More technically, we want to ask at what concentration of dissolved minerals in a static (no water leaving nor entering) water heater will we see back dissolving of existing deposits into the water. It depends too on heater temperatures and the water chemistry. I'll look further at the reaction and comment further.

I add that an on demand heater too can have serious trouble with clogging if the incoming water is hifgh in minerals. You would be better off installing a water softener.

Question: water was drained twice but it still makes noise

I have a Eco Water Heater that is 21/2 years. It makes a lot of noise.
Recently the heater was drained twice, and it still makes the same noise.
Any suggestions"

Ruben Castellanos - 11.16.11


Ruben, draining a water heater alone probably won't remove caked-on mineral scale deposits on the heater bottom or on its heating elements if it's an electric unit. You need to look at WATER HEATER SCALE DE-LIMING PROCEDURE.

Question: noisy attic water tank sounds like pipes banging together

My water tank in the attic is so noisy, my pipes sound like there banging together plus the toilet cistern is constantly overflowing! So frustrating. - 9/12/12



Often a very noisy water heater that bangs and clanks as it's heating up is due to scale formation. That might be worth checking out, along with how well the water pipes are actually secured.

I don't think that a water heater is going to have much to do with a toilet cistern problem - more likely that's a problem with the fill control valve in the toilet. Take a look at TOILET REPAIR GUIDE.

Question: oil fired water heater takes longer to come on

I have a oil-fired water heater,it is taking longer before it come on,so the temperature of the water is alot colder than it should be. Thermostat is set where it should be.What's the cause? - Anon 10/4/12



We had this problem on a gas fired water heater; the result was that too often the water was tepid to cool when it should have been kept hot. We discussed that problem in our article TANKLESS WATER HEATER INSTALLATION - but you don't have to replace the whole heater to fix this trouble.

A solution is to remove and de-scale the temperature sensor and control, but for safety and reliability it may make more sense to just replace the control or at least its temperature sensing component.

Question: water heater making scratching noises

(June 18, 2014) Bob said:

The HWH in my apartment is making a scratching sound at intermintent times usually from dusk on and continues most of the night. It sounds like a squirrel or rat scratching as confirmed by a pest mgt. company. However when you put your ear up against the HWH you deafinately hear the scratching sound coming out of it. I've never heard this before. What can it be?


Bob most likely you're hearing the turbulence in a water heater that has mineral scale formation on the heater bottom or heating elements.

Question: electric hot water tank making tapping sounds like a marble being tapped on the tank interior

Have an electric 80 gallon hot water tank that services one side of my house and a 40 gallon that services a guest bathroom on the other side of the house. We have hard water which can leave hard build up in sinks and showers if not cleaned regularly. Tonight I noticed that my 80 gallon tank is making periodic tapping sounds (much like a marble being tapped on the inside of the tank). I turned the electric off but it is still making those tapping sounds. Husband says not to worry about especially since the electric is off, but it is driving me crazy. What is causing it to suddenly make these noises? - A Harris 11/20/12


Indeed Mrs. Harris, a scaled-up water heater may make a tapping sound as hot gases form on the scale-coated tank bottom and as bubbles and water are disturbed in the tank as a result. If that's what's going on it's not always an immediate safety concern, as we've seen scale-coated water heaters remain in use for even a decade without a catastrophe. But ...

Watch out: if the water tank is not de-scaled the not only will the noises worsen, but it's possible for the tank bottom to be weakened, eventually leading to or contributing to a catastrophic water tank failure, described over at BLEVE EXPLOSIONS.

Question: water leaked into the water heater insulation between the tank and outer jacket - how do I get rid of it?

I have a new electric hot water heater. When installed the cold water valve was not tight and water has dripped into the LINING BETWEEN the tank and case. The bottom is full of water. How do I drain this? - Debbie 12/11/2012

Reply: how to dry out a flooded or soaked hot water heater tank


it is almost impossible to drain water that leaked into the lining of a water heater, though with GREAT care one might try removing a screw or two if they are present securing the bottom pan of the heater; an expert might drill a drain hole - but I do not recommend that approach as the risk is destroying the heater.

If not too much water dripped in, and if you let the heater got HOT, it should drive out the water as steam; I'd try that approach.

It's reasonable to dry out a water heater's insulation using its own heat if the heater has been wet with clean water and we do the dryout pretty soon so as to minimize the risk of a mold invasion.

For a heater that has been flooded with unsanitary floodwaters I'd prefer to replace the unit as I don't see how we're going to be sure our heater is not contaminated with sewage, pathogens, mold.

Incidentally, when the water heater gets hot you may hear a hissing sound and see some steam coming out of seams in the water heater jacket - if so that means you are successfully drying out its insulation.

Question: Brrring sound from water heater, intermittent at start-up

(Mar 26, 2015) Joanne said:
A Brrrring sound coming from the hot water heater - only intermittently. After turning on a hot water tap for a minute, the noise stopped. The sound seemed similar to a hollow sounding telephone ringing.


Thanks for the new sound for our catalog, Joanne. I can only guess that you are hearing a sound caused by water velocity moving through piping or a valve at or near the water heater, or perhaps even through it's dip tube. A mechanic's stethoscope can probably pinpoint the noise. Give that a try and let me know what you find.

Question: loud gurgling or boiling water sounds at water heater tank

Apr 23, 2015) ann said:
Is there a way to fix the tank from making loud gurgling and loping noises?

2015/12/07 John J Schmidt said:
My gas water heater makes strange sounds when the burner is heating the water. The sound is similar to that of rapid boiling water? What could cause this sound and how can I eliminate the noise. The water heater sounds like it is about to blow up?


Yes Ann

In the ARTICLE INDEX found at the More Reading links above see


Question: loud BANG at water heater start-up

(Apr 24, 2015) Jeff said:
We have two small water heaters upstairs to serve the upper part of the house. Occasionally we hear a very loud BANG (just one) as if someone dropped a very large encylopedia on the hardwood floor. Could this be from the water heaters?


Yes Jeff, though the bang is more likely if your water heater is gas or oil fired. Such BANGS may be quite dangerous - please see the discussion about water heater startup bangs and explosion sounds in the article above. Let me know if any of that leaves you with more questions.

Question: Clicking noise at gas water heater

(Oct 15, 2015) Deena said:
My gas water heater works fine but I can hear the gas clicking on more now heating the tank. Should I be concerned?


Deena I suspect you're hearing a noise caused by lime deposits.

In the ARTICLE INDEX found at the More Reading links above see


Question: anonymous reader has opinion about role of thermocouple in water heater noises

2015/12/10 Anonymous said:
So many of the threadsi have been reading are SO VERY WRONG. In instances of a single loud BANG or explosion type sound 99.9% of the time the thermal couple needs to be adjusted closer or further from burner depending on if you see a flame or not. Move thermal couple closer if no flame comes out of flu when you hear the bang and further if does.


Thank you for your anonymous opinion, anonymous but here you may be giving very dangerous advice - that could kill someone.

Rumbling banging water heaters - continuous noise when the burner is on - are most often traced to scale deposits.

A single loud bang at start-up is very dangerous if it is caused by the ignition of un-burned fuel, whether gas or oil. Such heaters should be shut off and then repaired by a trained service technician.

The thermocouple is a safety device that closes a gas valve if a safe flame is not maintained. I agree that misplaced thermocouples may prevent a gas burner from staying on but I would not expect that to cause explosions.

Readers whose water heaters cause a single BANG when the heater temperature goes from cold to hot - for example if the heater has been left off for a time or if you used all of the hot water in the heater, then stopped running water while the heater re-heated, should investigate water hammer - search inspectApedia for that term. You might need an expansion tank on your hot water system. If you're having this problem also look for water hammer induced dripping at relief valves. That's a dangerous condition too as repeated dripping can ultimately clog a valve leaving the water heater unprotected and thus risking a BLEVE explosion.

Separately: sometimes there is a single loud bang type noise at forced air heating furnaces - occurring when ductwork is heated and expands.

Cures for Water Heater Scale

  1. WATER HEATER SCALE DE-LIMING PROCEDURE exactly how to get rid of water heater scale, a common cause of water heater noises.
  2. WATER HEATER SCALE PREVENTION - how to avoid scale formation in water heaters
  3. More water heater noises and some recommendations are in the Residential Gas and Electric Water Heater Handbook [PDF] provided by A.O. Smith and linked-to

The articles at this website will answer most questions about diagnosing and curing noisy domestic water heaters and about the procedure to remove mineral deposits, lime, water scale, silicates, sulfates, aluminates, or silt and sand from a water heater tank. This website contains in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity.

Question: loud gurgling at water heater

(Jan 3, 2016) Eric Turner said:
Hi, I have a 8 year old water tank in a house that we just purchased. The hot water supply is fine however if somebody takes a shower and then goes over to a sink to brush their teeth etc. there is a very loud gurgling noise that comes from the hot water tank. Any idea what that is? Everybody keeps saying its sediment. I have flushed the tank and hot much came out. I do not know the history of maintenance of the tank.

Any ideas what would cause this issue?


I agree, more or less, withe "everybody" that sediment or more likely scale in the water heater is a common source of heater noises. Search for WATER HEATER SCALE REMOVAL to see more details about diagnosing and fixing the problem.

Question: roaring sound at water heater

(Feb 9, 2016) Jackie said:
What causes my hot water heater to make a roaring sound after the hot water has been running for a few minutes?



I don't know what sort of water heater you have - the situation could be very dangerous if a chimney fire is occurring - in that case have everyone leave the home and then call for emergency assistance.

Other sounds such as a popping hissing crackling may be due to lime in the water heater tank. Search InspectApedia for WATER HEATER DE SCALE

Question: uneven flame on gas fired hot water cylinder or calorifier

(Feb 11, 2016) Anonymous said:
jo heron have power miser hot water heater replaced burner assembly still have uneven flame turned down gas valve on gas line seems to make neater flame could my problem be high gas pressure
flag like


Uneven flame on different areas of the same burner usually means that the burner is dirty or partly clogged.

Question: flush noisy water heater with swimming pool muriatic acid?

(Feb 22, 2016) Donald Diltz said:
Can I pore Swimming Pool Muratic Acid in Tank and let Sit for one or Two Hrs to desove Lime, and Then Flush?

(Feb 22, 2016) Anonymous said:
I used to Flush Steam Boilers With Acid With a Circulating Pump for 8 to 10 hrs to Get Rid Of Scal. CAme
Out Shinning as a New Penny. These were 5 Pound Boilers. 55 Years Ago.



Please see the details including safety concerns, at the live link (in caps) in the this text in the article above

See WATER HEATER SCALE DE-LIMING PROCEDURE for the full article on the detailed procedure for removing lime and water heater scale.

Question: can't find water heater pilot light; water heater ignition problems

(Mar 1, 2016) Gene Anthony said:
Hot water heater keeps shutting down. I just checked the pilot light and found so much debris I can not locate the pilot light?

(July 17, 2016) Anna said:

Our heater does not ignite properly or at all, we were bleeding the radiators several times and on occasion it was working but then it stops again, it usually makes some funny noise which we think is due to trapped air but having bled all the rads several times I dnt know how this air gets inside or where to go from here

any advice would be greatly appreciated



IF your water heater is a gas fired unit and is rather new, there may be no pilot light, just an electronic or piezoelectric igniter that lights the flame when needed. Still a thermocouple or similar safety device will be installed to shut off the gas if the flame does not ignite or burn properly - that thermocouple may be the problem.


bleeding air from radiators won't have anything to do with whether or not a heating appliance ignites - that's a burner or combustion air problem.

The article above pertains to domestic water heaters - used to make hot water for washing and bathing. Home heating radiators are for heating space - rooms and are discussed beginning at AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE

that's probably what you are looking for.

(July 17, 2016) Anna said:

Thank you for the link,

I will look through the article
in fact we have one system that heats up both, water for sinks, showers, etc and the radiators, there is a small valve we need to move up or down, to have the radiators warmed up

Question: water heater popping noise

(Aug 5, 2016) anita said:
My gas hot water makes a popping noise when starting up. Is this normal ?



Search for WATER HEATER SCALE REMOVAL to read the probable cause, effects, and remedy for the water heater popping noise you describe.


Continue reading at WATER HEATER NOISE for electric water heaters or water cylinders, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Or see WATER HEATER WHISTLE NOISE - screaming tankless water heater diagnosis

Or see HEATING SYSTEM NOISE DIAGNOSIS for a more broad list of noises traced to heating equipment

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WATER HEATER NOISE FAQs at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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