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Water Hammer Noise FAQs-2

Q&A on causes water hammer or shock - banging pipes

• POST a QUESTION or COMMENT about banging pipes and water hammer noise: how to find, fix, or prevent banging water pipes or heating pipes

Questions & answers on diagnosing & fixing banging pipes & water hammer noise - hydrostatic shock.

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.

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Banging Sounds: Water Hammer Noise FAQs #2

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.

Isabelle

No it's not normal to hear water hammer for 15 minutes after working on the toilet.

More likely the problem was the specific velocity with which water was entering the toilet. Try opening the valve all the way - if the noise starts in that position try closing the valve a bit - and so on.

Indeed an arrester can stop banging pipes, though that cost *might* be a bit steep.

A Sioux Chief water arrester sold in the UK by Wickes is under £20 - but perhaps your plumber feels you need a larger device or that access to piping is going to require some costly labour.

Plumber charges vary widely depending on where you live but typically a plumber charges around £75 per hour.

So the cost estimate of £200 might be based on the plumber's estimate of 2 hours labour and the remainder in parts. OR the plumber may also have a fee for travel.

I have just had a combi boiler fitted, didn't gave a combi boiler before this. Now I have problem with banging popes when closing off hot tops and after cistern has filled up. Plumber wants to fit an arrester near stop.cock cost is about £200. Is this the best thing to cure the problem.

my husband shut off the valve to a toilet for a minor repair in the tank (something like a float) and when he turned the valve back on he heard water hammer and immediately shut the valve back off. i have read it is normal for this noise for the first 15 minutes, but he says we need to call an expert because it will cause damage. our home was built in 2004 but is a concrete slab, but should have the regulators in them. he knows 0% about plumbing, but i want to try to simply turn the valve back on to the toilet. what should we do? thanks!

Water hammer can do damage, causing leaks, burst pipes, damaged valves, and more subtly but more dangerous, leaks at tempeature/pressure relief valves can ultimately clog such a valve thus giving up an important safety device that is there to prevent a BLEVE - explosion.

We hear a loud hammering noise after flushing toilet or using water inside house. Is this doing damage? Can it be fixed without getting a new well?

There are both water-hammer reducing devices that can be installed on the piping near the valve and slower-closing valves that can be swapped in if needed. I agree it's important to fix this as water hammer can cause damage, leaks, even unsafe conditions (as it can damage a relief valve).

Please see the suggestions at WATER HAMMER NOISE DIAGNOSIS & CURE (found by searching InspectApedia.com for that phrase) or go directly to https://inspectapedia.com/plumbing/Water\_Hammer\_Noise.php

The new valve that shuts off the water on our pump and dump heating cooling system has caused terrible water hammering when the system shuts off. The old valve closed slowly and we had no problem. This sounds like it is tearing down the house. What do we need to do before this wrecks the pipes?

It sounds like water hammer to me, and a committee blaming the victim not the cause; record the sounds; consider installing water hammer arrestors.

I've read some of the water hammer comments and the noise seems to arise when a tap is turned off.However the water noise in my apartment in a 3 level complex consists of a loud "bang" (water turned on?)and then the sound of water rushing for about 5 seconds and then a loud bang when it stops. There's an interval of about 15 mins or more and it happens again.I thought it was the water gardening pipe that runs under my unit but apparently that pipe wasn't being used at the time in question (3 a.m). I'm aware water hammer is caused by, say, turning a tap off or a washing machine stopping water flow when its full (water stopped) but this noise (first bang) occurs at the start when the water is apparently turned on. My Building Executive Committee said the noise could be caused by tenants turning on and off their "over pressured taps" or from a dishwasher or washing machine. I'm glad you said a sound recorder could easily record the noise because I'm going to get one and try to get to the bottom of this. Any comment? Thanks

Sure Chrissy,

Just above in this article where you see the line

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

click on the live link shown in capital letters.

I am in a block of two flats. When my neighbour turns her outside taps on and off there is a terrible loud noise and shuddering. Can you tell me how we can fix this

The pressure relief valve won't itself cause water hammer, but as I said earlier it could leak dye to water hammer.

Check out the live link above at

Continue reading at WATER HAMMER NOISE DIAGNOSE & CURE

For water hammer explanation and cures. You'll see its probably a water velocity issue, fixed by adding a water hammer prevention device or a slow closing water valve.

My water heater was got replaced 6 months ago. Since then whenever the hot water gets turned on, there is a intermittent bang sound occurs. It only happens when hot water turns on.
Just wondering if this is related to the pressure valve. Any idea?
Thanks.

Marge

Thank you as well for taking time to let us know that our information on water hammer was helpful to you. I recall the drip irrigation comment and at the time figured, well what the heck, maybe this odd-sounding problem isn't so unusual after all.

So we moved the remarks into the article at WATER HAMMER NOISE DIAGNOSE & CURE. I'm especially glad that in the enormous sea of web pages you were able to find the information.

We welcome as well questions, criticism, and content suggestions: working together makes us smarter.

Thanks again.

Daniel

Your website is a miracle worker! An hour ago we started hearing a periodic "thump" from the laundry room--followed it to the washer's cold water line, where we could feel and see the pulse as well as hear it.

After trying several completely useless remedies (tested the water pressure, turned on faucets simultaneously, etc.), I found this website, scrolled through the discussion and came upon a comment from a reader with the same mysterious noise who determined that the problem was a faulty outside water timer trying to start a drip irrigation system.

Sure enough, that was our problem as well. The batteries were depleted enough that the system couldn't kick on. Thank you so incredibly much for this resource and freely shared expertise!

If the heat pump operation is not affecting the presence or absence of a noise, determined by shutting down the heat pump system and observing that the noise recurs, I'd look elsewhere for its source.

The noise occurs with the heat pump online and with it offline. After the plumbers replaced the pump, which had a built in check valve, the noise still occurs, but changed to a more random pattern.

It now occurs intermittently, sometimes while the heat pump is running, sometimes after the shower runs, or after/while the washing machine fills. No rhyme or reason.

Could debris become clogged in the manabloc and cause something like this? Is it safe to blow air through the manabloc? Running out of options.

Recapping the key issue

when the pressure is almost to the right level, the pipes (plastic) begin to shake and produce loud sound. The sound last for 15 to 60 seconds, and seems to stop when the pressure tank reaches the shut off setting. Tank is set to 20/40 psi now, when sounds started it was 40/60 psi.

I might experiment by closing valves to the ground-sourced heat pump to confirm that the problem does not occur except when the heat pump is online.

When I have seen this shutoff chatter at a well pump it's often been traced to a chattering check valve or control valve that's operating just enough to destabilize the pressure control switch near the cutoff pressure.

Any further thoughts on this? Still having the issue. Plumbers have now replaced the well pump, which didn't work. Lucky they said they wouldn't charge me if it didn't fix the issue. We are literally going crazy having to have plumber after plumber i here and never getting anywhere. Really need some help folks. Thanks.

The pump relay switch doesn't chatter at all either. Thanks for the help!

The pump is in the well. Plumbers have told me the pump is 1/2 HP and is likely barely large enough, should have been 3/4 HP.

As far as pump having trouble reaching cut-off pressure, the sound happened when the cut-off was set to 60 PSI and was identical when reduced to 40 PSI. The pump's amp draw was too high at the higher cut-off but was humming perfectly at the lower. I'm no expert, but it doesn't seem like its having trouble reaching the cut-off pressure.

Is the pump in the well?

Is the pump relay switch chattering?

Is the pump having trouble reaching the cut-off pressure?

We may want to pursue those questions and think further before just adding water hammer control devices.

I have a domestic well and a ground-water sourced heat pump that operates off the same well. I have pressure tank with 15 gallon draw and 44 gallon capacity.

Only recently, when water has been running for several minutes and then stops (like when the heat pump has run a cycle and stops drawing water), the well pump fills the pressure tank, when the pressure is almost to the right level, the pipes (plastic) begin to shake and produce loud sound.

The sound last for 15 to 60 seconds, and seems to stop when the pressure tank reaches the shut off setting.

Tank is set to 20/40 psi now, when sounds started it was 40/60 psi. The adjustment didn't help. I've now had two plumbers here a total of six times over two days and they can't find the issue. All they have managed to do is mask the sounds with foam pipe insulators, foam under the pressure tank, etc. - not addressing the actual cause.

They told me pressure tank operates fine, well pump is operating great too. Thanks for any suggestions, we are not sleeping well for a couple weeks now and need a solution. Appreciate the help!

Great question, Scott. My gut feel is no if you're talking about typical residential water piping materials and if we ignore the connections - it's a connection that is more likely to wiggle, weaken and come loose in response to water hammer.

There is some expert material failure research that digs more carefully into your question, as well as some theoretical modeling such as

• Schmitt, C., G. Pluvinage, E. HADJ‐TAIEB, and R. Akid. "Water pipeline failure due to water hammer effects." Fatigue & Fracture of Engineering Materials & Structures 29, no. 12 (2006): 1075-1082.
  Abstract:
  A numerical model has been established in order to simulate the propagation of pressure waves in water networks. The present model formulation is based on a system of partial hyperbolic differential equations. This system has been solved via the characteristics method.
  The current model provides the necessary data and the necessary damping of water hammer waves, taking into account the structure of the pipe network and the pressure loss. The numerical algorithm estimates the maximum pressure values resulting from the water hammer when closing valves in the network and consequently, the maximum stresses in the pipes have been calculated.
  In the case of simultaneous closing of several valves, the over pressure can exceed the admissible pressure. In this case, the severity of a defect such as a corrosion crater (pit) has been estimated by computing a safety factor for the stress distribution at the defect tip. This allows the applied notch stress intensity factor to be obtained. To investigate the defect geometry effects, semi-spherical and semi-elliptical defects are deemed to exist in up to one-half of the thickness of the pipe wall.
  The outcomes have been introduced into the structural integrity assessment procedure (SINTAP) failure diagram assessment (FAD) in order to obtain the safety factor value. Conventionally, it is considered that a failure hazard exists if this safety factor is less than two.
• Halliwell, A. R. "Velocity of a water-hammer wave in an elastic pipe." Journal of the Hydraulics Division, 1963, Vol. 89, Issue 4, Pg. 1-21
  Abstract:
  The general expression for the velocity of a water-hammer wave through a fluid in an elastic pipeline is evaluated. This result is applied to the following common practical cases: A rigid pipeline; thick-walled and thin-walled elastic pipelines with various longitudinal constraints; rock tunnels; and tunnels having a steel, or concrete, or steel and concrete lining.
  The results obtained are compared with those given in several standard reference books. It is shown that certain errors do exist, and considerable confusion does arise with these texts due to the fact that the assumptions made by the authors have not been clearly stated.
  Most of the confusion and errors in the texts are concerned with the effect of the external constraints or of Poisson's ratio, and the error involved is, in general, small (less than 10%). Nevertheless, this error may be important, and textbooks should make quite clear any assumptions made in deriving their results.
• Lahlou, Zacharia Michael. "Water hammer." Water Encyclopedia (2001).

Reviewing those and other sources suggest that some pipes could fail along the pipe length from water hammer.

Water hammer is not going to happen in drain pipes carrying wastewater - as expressed in your question - but rather in supply pipes that are under pressure.

Is it true that repeated high surges of water pressure can weaken pipe over time? If so, would this mean one could extend the life of discharge plumbing pipes by moderating the flow of wastewaater?

A water hammer arrestor can be damaged by mis-handling during installation, as Watts points out in their installation guide.
But typical water hammer arrestor design includes a sealed chamber that should not clog nor fail by leakage.

If the water hammer arrestor never worked satisfactorily I suspect that it was installed in the wrong location or that the wrong size was selected.

Water hammer an occur on a plumbing system as a "new" issue also if / when any valve is changed to a different type, such as a fast-closing zone valve on a heating boiler.

AUTHOR:R.S. (no email)

Do hammer suppressors go bad OR do they get clogged up and stop working because of that?

Searching InspectApedia using the search box just above and looking for "HOT WATER PRESSURE LOSS" finds this article that may help you diagnose the trouble you describe:

inspectapedia.com/plumbing/Hot_Water_Lost.php

I think I'd start by looking for scale in the water heater or calorifier or geyser or hot water cylinder - depending on where you live.

I have pipe banging I lose pressure on the hot water I still have pressure in the cold water what can cause this

How do I fix the hammering on my water heater

Bill, if you're sure this is a piping noise, yes the watering system could be the cause. See if the watering timer setting corresponds with the noise.

LOud knocks between 2am and 4|30am. NO inside or outside water is running at that time. Our home is on a water supply with 300 other homes. The water supply company has 3 wells in our community. DUring the day there is no knocking, thumping, sputtering of any kind. THe noise is on the side of the house with the meter.

Is pressure from water supply causing this when someone's irrigation, or swimming pool turns on, or flush of toilet from neighbor between the hours of 2am and 4:30am?

David,

Thank you for the nice comments. We work hard to provide authoritative, unbiased information, so we're thrilled when a reader finds inspectapedia.com useful.

We also welcome questions, content suggestions, and critique, so don't hesitate to ask. Working together makes us smarter.

We have a guest bathroom which is not all that frequently used. Recently friends from Poughkeepsie New York visited us here in Ontario. I was surprised to hear a loud banging sound from the plumbing when they use the Guest washroom.

This morning after their departure I reviewed this very helpful page and learned about the causes of this irritating hammer-like sound. Happily the solution was easy and one I learned about from this page. I adjusted the water flow by opening the water shut off to the side of the sink on the hot water side and the noise went away. Thank you very much! The next time my friends from Poughkeepsie visit I won't have to be embarrassed by my plumbing sounds. :-)

My hot water heater makes a hammering noise when I've done a few loads of laundry. What can the cause of this be? I still get hot water but the noise worries me.

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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.

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