Banging pipes & water hammer noise diagnosis, cure:

Water hammer noises in plumbing is also called hydrostatic shock. Our page top photo shows a water hammer noise suppression device produced by Oatey and available at building suppliers.

This particular water hammer noise suppressor is interesting because it's designed to be added to a hose bib or washing machine hose connection by a homeowner, avoiding having to cut and solder pipes.

The articles at this website will answer most questions about plumbing noise associated with water hammer or water surge, including the diagnosis and cure of water hammer noises as well as many other building plumbing system inspection or defect topics.

Water Hammer Noises Diagnosis & Cure FAQs

Some of the banging pipe noise and water hammer FAQs discussed below are adapted from information provided by the Watts Regulator Company in a 1973 publication. - seeReferences or Citations .

These questions about water hammer and water hammer noise causes & cures were posted originally

at WATER HAMMER NOISE DIAGNOSE & CURE - be sure to review that article.

On 2021-01-22 by Denise - It's definitely not water hammer

It's definitely not water hammer as the first plumber ruled that out. The house was built 2009. I did look at the links you shared but nothing jumped out. If it's due ducts expansion, how could it be that the banging occurs when I haven't used the furnace for 8 hours?

Hi,
Attached is a summary. You will need to put together the pages horizontally, not vertically.

The main source of noise is in the wall between the 2 bathrooms (approx 15' in length) so I'm not too sure I'd be able to pinpoint it much further with a mechanical stethoscope unless I cut into the drywall.

Denise

On 2021-01-22 - by (mod) - Example noise log helps track down banging pipe noise

If you've pinpointed the noise to a specific wall it may be time to take a look into the wall: by cuts or a boresope; or you might want to bring an experienced building inspector or sound engineer onsite. We need to relate the apparent noise sources you suspect that seem in your log to be disparate.

We assembled your Noise Log data vertically simply so that it could be read by most viewers.

[Click to enlarge any image]

 

On 2021-01-22 - by (mod) -

For a confounded noise track down such as the situation you describe, even though it's difficult, the most-profitable course of action is a combination of

- locating the noise source by amplitude (instruments can help)

- locating noise sources by noting what equipment is running or not running

| - relating noise to exterior conditions: temperature, sunlight, weather, air movement, occupancy, etc.

For that the noise log I cited earlier and that you've attempted (example above) can help

 

On 2021-01-22 - by (mod) -

Denise, Steve and other readers: Please find your question and my detailed reply now at the Reader Q&A section near the bottom of the article above on this page. You may need to clear or refresh your browser cache to see the updated page. We welcome your further photos, comments, questions.

On 2021-01-22 by (mod) - trouble finding source of banging pipes & alternatives to water hammer noise

Sorry, I'm guessing that you try to attach a document. Comment box only allows people to attach photos. Perhaps you can paste in a summary as a comment.

Also consider that the noise you hear may not be water hammer, but other sources of banging noises in buildings such as expanding metal duct work or HVAC noises or other thermal expansion and contraction of materials.

See these two diagnostic articles

• BANGING HEATING PIPES RADIATORS
• BANGING BOOMING NOISE DIAGNOSIS & CURE
• WATER HAMMER DIAGNOSIS
• WATER HAMMER CURES
  

On 2021-01-22 by Denise

I have poured through the resources here and have found nothing that comes close to what I'm experiencing.

I'm ready to call someone in to cut into the wall in the upper level as the sound is so unpredictable and at times can be very loud. Attached is a summary of just today and late last night....interested if you can see anything that I'm missing.

Thank you. I will look at those links later today and can perhaps upload audio. The trouble is, the sound isn't constant or always repetitive, so it's hard to know when I'll hear it again after the initial bang sound.

It can also occur when the furnace hasn't cycled for hours so it's hard to pinpoint if that is the problem or not. I'll give you an update....

On 2021-01-19 - by (mod) -

Denise

Indeed we need more sound recording and tracking work at your house; sounds caused by an event in one location such as a heating system can be picked up and transmitted by nearby materials, so ducts can conduct piping noises and vice versa.

NOISE SOURCE LOCATION - LOG FILES

and other suggestions are

at NOISE / SOUND DIAGNOSIS & CURE

On 2021-01-19 by Denise

The past 4 months I've been getting random banging sounds from under the sink in the ensuite. It can happen day/night, at times where no water has been used in the house for hours. The sound comes from somewhere along the pipe in the wall. The house was built in 2009.

Plumbers have come out, it's not water hammer although he drain all water from all taps in the entire house (heard the sound 4 hours later).

I've turned off the main water line at night and have still heard it. There is no leak, water stains, etc. The last plumber said it may have to do with heating ducts causing expansion and contraction?

(Not sure what the connection is with that, there is a heating vent in each bathroom) The sound is definitely coming from under the sink and it carries over to the pipe under the sink on the other side of the wall in the other bathroom.

I cannot find any pattern as to what triggers i (i.e. it's not after a shower or when the toilet has been flushed, etc.). Any help would be greatly appreciated as it's extremely annoying. I even hear it when I'm on the main floor as the sound comes down through the ceiling. Sometimes I don't hear it all day other times I hear it 10 times in one hour.

On 2021-01-15 by Steve

Ok thank you for your reply, much appreciated.

On 2021-01-14 - by (mod) -

Steve

I doubt that anyone can give a reliable exact explanation of the noise that you were hearing now from simply a brief text note. But it's possible that you were simply hearing normal plumbing noises that would be better isolated if there were insulation in the common wall between your two living spaces.

That may be something you can add for example by pumping or blowing in foam or a similar sound deadening material. It won't be perfect because the wall framing will still conduct some sound but it should reduce the issue.

On 2021-01-14 by Steve

I live in a townhouse with common walls, after my neighbour renovated his bathroom I can now hear when he uses the shower, which is annoying and due to his shift work is in the very early hours of the morning.

It's a loud, constant white noise type of sound rather than a hammer.

Your advice as to the cause would be greatly appreciated.

On 2020-12-24 - by (mod) -

Roland

Indeed that sound could be coming from your pump. I've encountered exactly that problem in a water system that we recently installed. It depends on the type of pump and where it is installed. Maybe you could tell me more about that.

On 2020-12-24 by Roland

Recently added a circulating line and pump to my water heater. As a precaution, I also added an expansion air tank. I am on city water, so I have great dependable water pressure. I do have an irrigation system, but that is closed off because it is winter.

Since the install of my pump, I am experiencing a tapping when a faucet is open an water flowing. I have icolated the noise to be a backflow valve, which was previously in place, but now is making a noise as if it were opening znd shutting constantly while water is flowing....approximately every "second". Could the circulation pump cause this? Could the expansion tank cause this? These are my only two main variables.

Thanks,

 

On 2020-12-23 - by (mod) -

Tony

Most likely one of the causes listed in the article above.

Try closing your main water valve a bit.

On 2020-12-23 by Tony

What is causing my water pipes to randomly have a low knocking noise and I just put in a new water heater about a week ago but this was going on before I put the new water heater in?

On 2020-12-17 - by (mod) -

Fred:

Thank you very much for taking the time to write this very helpful water hammer noise update.

You can teach an old dog new tricks.

I will add to our list of steps in tracking down noises in plumbing systems, meters, etc. to remember to check not just your own but other nearby water meters, pipes, etc. that may be those of a neighbour.

On 2020-12-17 by Fred O

RE: "IF water is flowing in the home but the water heater isn't registering that water use then the meter is probably damaged and that might indeed be the noise source."

I FINALLY have the answer (probably) and you were essentially right --
When the thumping noise was occurring, I checked my next door neighbor's meter, which is adjacent to mine and next to the street. I could feel the vibration there and the meter indicator was spinning rapidly and jerkily. So the problem is a meter -- my neighbor's.

I have notified the city water dept. (I rarely see the neighbor).

On 2020-11-30 - by (mod) - water meter not "water heater"

Right, and apologies Fred; we have so many readers, comments, questions that when I'm getting behind I may try dictating a reply and sometimes miss the computer's typos- embarrassing both myself and the software and hardware involved.

Don't forget to check for water that's running in secret, such as a running toilet.

On 2020-11-30 by Fred O

RE: "IF water is flowing in the home but the water heater isn't registering that water use then the meter is probably damaged and that might indeed be the noise source."

I think you meant "water meter" rather than "water heater." When water is flowing, the meter does register the flow. But since we can hear the noise only when in the garage and we normally do not run water when we are out there, the meter does not show flow when we hear the noise.

The noise is intermittent, only a few times/day. I still suspect either the meter or some unknown vibration in the water main under the street. But then, neighbors do not report hearing a similar noise.

I sent a message to the city building inspectors similar to the previous I posted here. No answer yet. I've not called my plumber since the hot water tank was replaced.

Thanks,
Fred

On 2020-11-27 - by (mod) - IF water is flowing in the home but the water meter isn't registering

Fred

IF water is flowing in the home but the water meter isn't registering that water use then the meter is probably damaged and that might indeed be the noise source.

On 2020-11-27 by Fred O

RE: "It might be interesting to use a mechanic's stethoscope on the water pipe at several locations when you are hearing the mystery noise".

Thanks again for your advice. I can feel the pipe shaking slightly where the pipe is exposed. Also see below.

Today, a new development. Rather than "thump, thump, thump" at a moderate volume, we heard "tap, tap, tap" at faster cadence and lower volume. We could also feel the tapping on the pipe but it was not as prominent as earlier.

I went out to the water meter, which is in a box just below ground next to the street and I could feel the tapping on the meter. Again, no water flowing and the spinner on the meter did not move. A bit later, the thumping returned, louder than the tapping but I think at lower volume than the thumping before.

I now suspect the meter. A week ago, I called the Prescott building inspection dept. and left a message They have not called back. I plan to leave an email msg.

On 2020-11-24 - by (mod) -

It might be interesting to use a mechanic's stethoscope on the water pipe at several locations when you are hearing the mystery noise

On 2020-11-24 by Anonymous

RE: "If there were really no water movement through pipes then what might cause pipe "noise" in the first place?"

A couple times I've looked at the water meter when the pipe was thumping but did not see any movement. Once, I noted the position of the spinner and saw it in the same spot 30 minutes later.

"Possibly some other, even outside, mechanical noise source that's being picked up and transmitted by the piping or a local pressure booster pump or there is a leak somewhere that's not been found."

I intend to try feeling the meter for vibration next time I hear the noise. But it occurs only occasionally. Only pump is the hot water recirculator and that's on a count-down timer that I installed myself. As for leaks, the water bill has not been elevated.

Tis a puzzlement. Thanks for your thoughts. I've asked my city building dept. but they have not answered my query.

On 2020-11-22 - by (mod) -

Fred

Thanks for an interesting question. I'm stumped. If there were really no water movement through pipes then what might cause pipe "noise" in the first place?

Possibly some other, even outside, mechanical noise source that's being picked up and transmitted by the piping

or

a local pressure booster pump

or there is a leak somewhere that's not been found.

On 2020-11-20 by Fred O

This is a reworded repeat of a query entered yesterday that has not appeared.

I have a somewhat different water pipe noise problem.

A couple weeks ago, I noticed noise -- thump, thump, thump, -- about 2-3 times per second and continuing for about a minute coming from the water line in my garage. The line, (PEX pipe) installed 2 years ago to replace the original line that was leaking, runs from a meter by the street, underground and then up through a hole in the garage floor to the ceiling and finally around two walls to the shutoff and pressure regulator next to the hot water tank.

The noise is not very loud. I can usually hear it only when I'm in the garage. But I can feel the pipe shaking when thumping. I'll guess it occurs a few times each day.

My plumber initially said it was caused by a failing regulator but then he found the thermal expansion tank was full of water. He attached a pressure gage to a spigot and told me to not run water until he returned in an hour with a new tank. The pressure stayed constant (~60 psi) until he returned so he replaced the tank and not the regulator.

Next day I heard the thumping again. The plumber convinced me to also replace my 16 year old Rheem water heater although in my experience, Rheem tanks last over 20 years.

But the following day and subsequently, I've heard the thumping again. Twice when this was occurring, I checked the water meter to verify no water was running. Once I went in the house and opened a faucet but the thumping did not stop right away.

The house is in Prescott, AZ and was built in 2004. The supply pressure is rather high -- 110 psi and about half of the water lines in my development have failed but I believe the failure is due to improper filling of the trenches with chunks of basalt rock rather than the proper sand bedding and shade fill.

The replacement line was properly installed and inspected by the city. Another nearby development is at the same altitude, thus likely similar pressure but homeowners there do not report water line failures. Several neighbors I've asked do not report not hearing similar noises.

What to do next?

On 2020-10-19 - by (mod) -

Les

Knowing nothing about your home and its environment we're left with my best shot at an organized list of things to check for water hammer as given on the page above.

Please take a look there as a good place to start.

If anything you find at InspectApedia seems incomplete, confusing, or wrong please ask - or complain as it'll help us both.

On 2020-10-19 by Les

Have done the following to try and fix water hammering problem: changed valve kits, flappers etc., new water inlet hoses, new pressure valve, inspected roof vents, drained system, installed hammer arrestors. Still have the problem, ANY IDEAS? Help!

 

On 2016-03-21 by (mod) re: my radiators are banging so loud that a pipe in the basement popped

Sure Antoine,

at the CONTINUE READING links just above see the live link for


Or see BANGING HEATING PIPES RADIATORS

to diagnose and repair this trouble. Usuallly the problem in your case is condensate is not returning.

On 2016-03-21 by Antoine

my radiators are banging so loud that a pipe in the basement popped. i sealed it temporarily with a screw. i located a leak , due to the radiator not being tightened enough.one of the small pressure valves in the basement is leaking water at the part where only steam is supposed to come out.i am so done... help me please.

On 2016-01-21 by (mod) re: i installed my water arrester at the pressurize tank.

Robert

It may be that the installation location you chose is not the best - see the notes above about locating near highest fixture.

On 2016-01-21 by robert

i installed my water arrester at the pressurize tank. Our water source is an overhead tank, water pump is located lower than the source and check valve next and pressurize tank after..... but hammering still exist and annoying every time the pressure switch shut-off. please give me more details location of tapping the said device. thanks

On 2016-01-16 by (mod) re: noise like something falling in the wall

Perhaps cooling metal ductwork

On 2016-01-16 by Rosie

A noise that sounds like something falling in the wall when the heat turns on or off?

On 2015-11-13 by (mod) re: violent radiator hammer sounds in my building apartment

Search inspectapedia for


banging radiator noise

For some suggestions you can share with the building owner.

On 2015-11-13 19:46:50.722183 by Robert F

Hello,
I live in Plymouth Wisconsin. Are you aware of, or can you direct me to, a website/phone number which will help address violent radiator hammer sounds in my building apartment? I have approached the building manager and landlord to address/repair the problem and they have been dismissive.
Do I have any recourse other than treating this as tenant vs. landlord legal matter?
Thank you.
Sincerely,
Robert F
bobbyofallon@gmail.com

On 2015-11-08 15:33:26.517660 by Andy

Thanks. I'll give it a try.

On 2015-11-08 by (mod) re: where to install the water hammer arrestor.

I'm over my head here Andy and uncertain between following the mfg's generic instructions - which places the arrester ahead of the highest fixture - and your observation that you find the hammer occurring near the point of water entry; from your description it seems reasonable to install the water hammer arrestor ahead of the booster pump.

And you'll be conducting some water hammer science: do let me know if that does the trick.

On 2015-11-07 by Andy

Follow up on Reader Question: where to install the water hammer arrestor.

Thank you for your advice. Regarding the size of the arrestor, there is really only a single device: the booster.

The main line into the house goes directly to the pressure regulator/booster pump, and then on to all of the "fixtures" in the house. Since the hammer appears to be between the main shutoff valve on the supply side to the house and the regulator, would this be considered "one fixture", or should I attempt to cover all of the fixtures in the house past the booster pump? Thanks again.

Question: How to Identify Water Hammer Noise in Buildings

(Apr 25, 2015) Chad said:
While water is running through the shower, I suddenly have the water shut off, and there is loud banging in the walls. After reviewing multiple posts, I have not see that others are havinng issues with the water shutting off. Would this still be considered water hammer, or something else?

(July 3, 2014) Krystyl Cruz said: when I flush the toilet there is a loud sound like a jackhammer

When I flush the toilet, a few seconds later (when the water is refilling) a loud sound like a jack hammer comes from the wall behind the toilet. Sometimes if I turn the faucet on in the sink the banging will stop, but if I turn the faucet back off the banging starts again until the toilet stops running.

(Mar 1, 2015) D said:
When turning off hot water I hear a banging

(June 9, 2015) Anonymous said:
When toilet is flushed or cold water is run there is a loud noise which goes away when the hot/cold water taps are run. This only happens in warm weather.

(Sept 10, 2015) Robin said:
When I turn my bathroom faucet on, the pipes start clattering. It mostly does it when I turn the hot water on. Could this be caused by dirty inlets in the faucet? I didn't have this problem until the plumber installed a new hot water tank.

Reply: the above are all examples of water hammer noise

Thanks for the questions, Chad, Krystyl and D and others. If the water flow stops, that is a separate problem from the loud banging. I'd guess that the banging is indeed water hammer - which can occur when water supply shuts off suddenly in a piping system. But the banging is not likely to itself be the *cause* of the sudden loss of water. That sounds more as if a valve is closing.

You are almost certainly describing a water hammer problem. I've found just the symptoms you describe including that opening a faucet, because it changes the flow rate and pressure in the piping, can move the flow rate off of that speed that is causing the horrible banging sound.

Since water hammer is a feature of water flow velocity and is affected by loose pipes, or valves that close suddenly, I'd look in detail at exactly what has changed; try slight adjustments to water pressure.

Robin: Of course you'll want to clean out dirty faucet strainers but I doubt that's the source of trouble unless those conditions have changed the water flow rate. In fact water hammer is more likely to appear when water velocity is faster so cleaning out clogs may increase it.

Question: does water hammer in my plumbing system cause damage?

What effects can water hammer have on my house plumbing system? Other than making noise, does it actually hurt anything?

Reply:

Water hammer causes a sudden "banging" of water supply piping that creates movement and stresses in the system, not just annoying noise.

Water hammer can cause loosening of water supply piping connections, leading to plumbing leaks and related damage

Watch out: Water hammer shocks to the water supply system are more serious at higher operating pressures. On hot water heaters the TP valve is usually set 20 to 30 psi above the anticipated maximum system water pressure. This is high enough that the relief valve won't leak or spill when water hammer occurs in thte system. But at higher water pressures, say 70 psi to 90 psi, the relief valve may be damaged or leak when water hammer occurs.

At our article on WATER PRESSURE REDUCER / REGULATOR you 'll see that we recommend against operating a home at pressures above 70 psi because of the increased risk of plumbing system or plumbing fixture leaks. [10] paraphrased

Question: can I record water hammer noise? Loud banging that isn't water hammering?

(Oct 27, 2011) Ian Anderson said:

Hello, is there sound recording equipment to prove water hammer noise from neighbours flat?

(Jan 15, 2012) Anonymous said:

Mike I have a 75 gallom power vent gas hwh the home is well water ther is a check valve on the cold water side of the hwh there is also a expanchion tank n both are between the ball valve and hwh i am getting alot of load banging on both the hot and cold side when water is running and it isnt water hammering because i put air aresters on system its happening when both cold and hot are running I was wondering if it was the check valve causeing the banging sound ?

Reply:

Ian, you can use any recording equipment, even a sound recorder on a cell phone to record the sounds you describe. I've done that with great success. If you are using a cell phone hold it against a noisy wall or ceiling for strongest sound transmission into the device.

Anon: Putting air arresters onto the system may not have been enough to cure the water hammer if they were too small in capacity.

Question: loud hammering noise wakes me up

(June 21, 2012) jt said:

I am hearing loud hammerins noises, loud enough to wake me up, in the middle of the night. It sounds like the tap is being turned off and on but this is not the case.
When I do use the tap, it only makes the banging noise if I turn it on and off very sharply.
What can I do?

Reply:

JT, if the loud hammering noises are in the water supply piping, it seems most likely that someone is turning water on and off, or a well pump is turning on and off on its own - if you have a well pump try checking out causes of the well pump "turning on by itself".

Securing loose piping and installing a water hammer control device (described in the article above can also help stop the problem.

Question: various banging, moaning, clanging plumbing noise complaints

(Sept 2, 2012) Tom said:

The noise is not as much about banging but a loud moan in the hot water line between the washing machine and the Master bath tub supply, although if you flush the toilet the noise stops until the tank is filled.

Have tried everything from turning off the water and draining all the lines and refilling each line in different sequences, nothing works?

(Jan 4, 2013) Ted L. said:

Thermal Expansion: When water is heated in the Water Heater it causes water to expand thus an increase in water pressure.

A Code requirement and solution is to install an Expansion tank on the cold water supply line ahead of the Water Heater. The rubber gland will absorb the expanded water and release it when a tap is opened. Expansion problems prevail when no water is being used and the tank is heating.

(Jan 19, 2013) Gary S. said:

I live in a 37 unit appartment and at nightime I can hear a low pounding noise in the distant Would this noise affect the heat temp in my unit. I have hydronic heating.

(Feb 25, 2013) Ykip said:

I experience a severe water hammer when turning on and off the bathtub spout. How can I fix the water hammer arrestor on it? It seems impossible. The water pressure to the house is normal and about 70psi. I appreciate anyone to help me. Thanks,

Question: Rumbing pipes under the toilet

(Mar 5, 2014) Help! said:

My house pipes seem to rumble under the toilet. The toilet is upstairs
I have a water tank in the loft and also a water tank in a cupboard upstairs.

The time does not appear to be defined by any one event (the heating coming on, the water heater turning on, washing machine going).
However this rumbling also sometimes goes 'off' if you sit on the toilet or simply walk into the bathroom.

The times are also intermittent. Sometimes it doesnt rumble at all, sometimes once every hour, sometimes every few hours or sometimes every 20 minutes (which drives me mad!)
But the 'rumble' does cease when the toilet is flushed (for a time)?

I am not in any way DIY minded so do not feel comfortable investigating the problem myself.
However wondered if you could perhaps assist in telling me what it is and assumedly i need to get a plumber - how much it would potentially cost to fix?
Thanks,

Reply:

Help.

This rumbling doesn't sound like water hammer. Water hammer is a percussive "BANG!" that or maybe "BANG BANG bang clank" short duration clamor that occurs when water is running (fast and at high pressure and flow rate) and then is suddenly shut off.

If it's not a coincidence, sitting on the toilet or walking into the bathroom wouldn't be expected to impact a water hammer problem so I suspect we're looking for something else.

Let's start by trying to isolate systems to find out which system is responsible. I suspect we're looking at something related to heating, not water supply, or a water heater.

Water heaters that have formed a scale deposit on the heater bottom will often make an ongoing rumbling popping sort of sound * when the heater is operating * that is, when it's heat source is on.

So when you hear the noise let's notice what systems are running and which are off.

Or you could turn off the water heater for say half a day and see if the noise abates.

Search InspectApedia for "Water Heater Scale" to read more about this hypothesis.

Keep us posted and we'll pursue it.

Question: water pressure booster pump noise

(Mar 9, 2014) Anonymous said:

water pressure booster pump noise going through my water pipes what can I do?

Reply:

If th problem is not a banging when water is turne off in the building then I guess you refer to the transmission of noise from the pump motor. You'll want to look at sound-isolating fixtures to isolate the vibrating piping from the building structure. Regular pipe hangers won't do it.

Question:

(Apr 3, 2014) ron said:

at our cottage the water system was fine. its a submerable pump with an air bleeder valve just before the electrical switch. its 25 yrs old. however it seams that when we replaced the tap in the shower the pipes started to shake and water spurts out. This happens after we have used the water system for a bit then it keeps banging/shaking/spurting. also when filling the toilet. thanks

Reply:

Ron,

It's not a complete surprise; sometimes when we simply change the water flow rate we change the vibration behaviour of the system.

It might be diagnostic to open a tap when you hear the banging water hammer noise. Openign a tap elsewhere changes the pressure and flow in the system.

I'd also double check that nothing has changed on the water supply end.

Let me know what you find.

Question: banging noise in pipes at night, 3-5 seconds apart, 7-8 bangs

(Apr 3, 2014) Dave said:

My question is this. At night i am hearing a banging in the pipes every 3-5 seconds of approximately 7-8 bangs. They can be felt when touching the pipes from the laundry room. They are not overly loud. The seem to go away for a brief time when I run the water at the lowest faucet in the house. Any ideas?

Reply:

Dave

You're probably describing water hammer as we discuss it above.

Question: trouble tracking down water hammer noise

(Apr 19, 2014) Lynn Pepe said:

For the past 5 days, we hear what sounds similar to water hammer, can not pinpoint where it is coming from. Tbis happens any time of day or night, does not seem to be related to turning water on or off. We have tried shutting down the main and running the water out several times. We have had the water company to check. what can this be???

Reply:

Lynn, I would be just shooting in the dark to guess very specifically, but surely if you hear the sound when water into the building is shut off completely it's not a water supply system problem. At that point I'd be looking at hot water heating, steam heating piping, and if those are ruled out, I'd be looking for other sources of mechanical movement.

Question: will the Temperature & Pressure relief valve protect the hot water tank against water hammer damage?

Will the T&P valve protect the tank against breaking from excessive water hammer? - Watts

Reply:

An "excessive" water hammer is an abnormal but momentary condition that causes a very brief surge in water system pressure. The pressure-relief component of a temperature and pressure relief valve can only discharge a verly limited amount of the surged pressure during the moment of shock of the water hammer event, possibly none.

If water hammer is causing frequent opening of the temperature and pressure relief valve there may also be a risk that the frequent passage of hot water through the valve deposits scale that eventually accumulates to a level at which it prevents safe reliable operation of the valve in an emergency.

And the fact that temperatures inside the hot water storage tank are elevated above cold water temperatures makes no difference - with the exception of the warning we issue next.

Watch out: if the hot water tank is in an abnormal overheated condition, that is water in the tank has become superheated above its atmospheric boiling point water hammer could actually lead to a water heater tank explosion. According to Watts Regulator Company, "Water hammer conditions are believed to be a partial factor in starting off an explosion of overheated tanks besides "pressure heat rupture". [10] paraphrased

Question: septic pump check valve noise

5/29/14 Naaj said:

Water-hammering noise from check valve in septic sump pump…solution?

Reply:

Check that you don't have multiple check valves installed on the same piping system. If there is only one then you're ok on that score and you'll want to install an anti-water hammer noise product such as those discussed above.

Question: ball cock in the water tank in loft causeing water hammer

(Oct 18, 2014) mr conner said:

can it be the ball cock in the water tank in loft causeing water hammer

Reply:

No, not directly but possibly indirectly:

Water hammer is an effect of the velocity of movement in water pipes along with pipe dimensions and layout, combined with a sudden STOP! of water flow. Any valve can "cause" the effect to be heard. Some plumbers install slow closing valves to reduce the problem but you'll read other solutions in the article above.

Question: banging pipe issues

(Nov 3, 2014) Hope said:

We recently had issues with banging pipes in our home. A plumber recently came out and replaced the water pressure regulator along with adding an expansion tank to our water heater but now after a month or so the noise is back and isn't happening when the water is running like it was before but when the water softner is running. Please help...what could the problem be now?

Reply:

Hope,

I'd like to help but with not a shred of information about your home, piping, water supply, pressure, valves, usage, etc. my best advice remains in the article above. If any part of that is unclear please just ask.

Question: banging pipes and water softeners

(Nov 18, 2014) A Kang said:

At my home (Cypress Texas), we hear water hammer noise at the end of water softner regeneration cycle. There was no water hammer prior to installation of water softner. I brought in the water softner installer and could not figure out why and told may be water pressure is high when the regeneration cycle occurs. He changed regeneration cycle time from night to afternoon and we still have water hammer.

The regeneration cycle is after 10 days and lasts for 1 hr 45 minutes. Did water softner not installed properly? The house was built in late 2010 (by village builders a subsidiary of Lennar Homes). We had water water softner installed in 9/2011. We purchased this new home and moved in April 2011. I called in a plumber and he was not much help. I am considering to contact the plumbing company (New Tex) who did the original plumbing in the home. May be they can figure out and fix this problem. Any guidance you have. Thanks

Reply:

AK

Ask about installing either an appropriate water hammer control device (described in the article above) or a slow-closing control valve on the supply to the water softener.

Question: why does water hammer noise suddenly appear in a building?

(Apr 12, 2015) Carl C said:
Why would my plumbing suddenly start making water hammer bangs when it never did before? Nothing changed in my plumbing or any appliances, yet I start hearing significant water hammer. Yesterday, all was quite as it has been for years, then today I hear water hammer. Any ideas?

Reply:

Great question, Carl. I can speculate that

- water pressure may have increased at the source

- a pipe or fixture has come loose

- a control valve has been opened or closed to a different extent than previously

As water hammer is related in large part to velocity of flow and sudden stopping, a change in a valve can be enough. Certainly something has changed so let's start with that assumption.

Question:

(Apr 15, 2015) lose prime said:
Replaced pressure tank with bigger capacity tank. Water now loses prime every so often. Could it be the preassure switch or backflow valve got debris in it?

Reply:

Lose

That's a smart guess, particularly if your water pump uses an internal check valve or if such a valve is installed at the pump, else I suspect a failing foot valve. I'm not clear why this is a water hammer noise question.

Question: water hammer noise after installing a booster pump for water pressure

2 Nov 2015 Andy said:

I've recently replaced a booster pump in my residence. This new pump switches on Immediately on noting a pressure drop (water being used) versus the old one which had a timer delay before powering on. I installed a Honeywell pressure reducer on the supply side of the pump and my total pressure is around 60. All should be good - but when water is used, there is quite a hammer going on.

The hammer appears to be on the supply side of the pressure reducer/pump (because I hear a copper bang) versus on the output side of the pump (house flow which is plastic).

I thought about maybe installing an arrestor, but since the hammer is on the supply side, I have no idea where to install it. I also find it odd that I have a hammer on the supply side.
Any advice would be appreciated. The pump vendor is suggesting a pressure tank on the output side, but until I understand what is going on, I don't want to start modifying plumbing. Thanks.

Reply:

Interesting; Indeed I'd install a water hammer arrestor on the side of equipment, valve, or device where the hammering appears to occur; Anywhere close to that point should work.

Usually we install the water hammer arrestor between the shutoff valve and the incoming water supply line - close to the valve. Or we may need to install a water hammer arrestor on both hot and cold water piping systems. If that doesn't work for you I suspect the water hammer arrestor was not properly sized.

Here is what water hammer manufacturers say

"The location should be at the piping serving the fixture(s) and normally between the last two fixtures. " - J.R. Smith Manufacturing Co.

"Water hammer arresters shall be specifically sized and have sufficient volume of air to dissipate the calculated kinetic energy generated by closing residential or commercial faucets or valves. Arresters shall be installed on both hot and cold lines on the supply stops where applicable. Arresters shall be approved for installation with no access panel required." Sioux Chief Manufacturing Co.

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Continue reading  at WATER HAMMER NOISE DIAGNOSE & CURE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER HAMMER NOISE FAQs-2 - more-recent questions about banging pipes traced to water hammering & hydrostatic shock.

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