Plumbing Noises

Plumbing can make many weird noises which can have many causes and; sometimes, they're not easy to isolate and fix. I've tried to collect common causes given on

A Single Bang, Knock, Clunk or Clang

Such sounds are usually caused by a phenomenon called 'water hammer.' Water hammer doesn't accompany flowing water, so if your sound occurs while water is running, it isn't water hammer.

Water hammer happens when you turn OFF a water flow suddenly (like a dishwasher, a clothes washer, a toilet or even closing a hand faucet suddenly. Shutting off the flow suddenly sends a pressure or shock wave down the water line through the water shocking the pipes and creating the 'hammer' noise.  These shock waves travel faster than the speed of sound and can exert very great  instantaneous pressures.  Over time, water hammer can damage pipes, valves and eventually weaken pipe joints.

Most modern homes have devices called water hammer arresters ( they're called various things such as air chamber, air cushion, water capacitor, etc.) . They are air filled chambers connected to the plumbing that let the pressure wave dissipate harmlessly into a cushion of air. If your banging has been happening forever you may not have one.

Sometimes these arresters become waterlogged. Try this. Turn off the water to the house at the entry. Find the lowest faucet in your house--often this is an outdoor garden hose faucet--open this faucet and then open a few of the indoor faucets at high locations such as upstairs or at a wet bar and let the low faucet drain for 5 minutes or until it stops dripping, whichever takes longer. Close all the faucets and turn the main back on.  Note:  When you first start using water again there will be air in the lines and it may spit and sputter with some vigor.

If this fixes it you have a defective or waterlogged arrester.

Here's a more extensive article on water hammer arresters.

Fog Horn, Bleating, Wailing, Moaning, Humming, Screaming
Fluttering, Rattling, Chattering, Motor Boat, Whistling, Oboe

Speedy Jim Mais said on

Often a faulty toilet ballcock (fill valve) will cause resonance sounds like these. At least it's easy to check -- here's how to tell if this is the cause. Close the supply valves to all the toilets. If the noise disappears, open them one-by-one till the noise starts again. Replace the ballcock in that toilet.

If there are no shut-offs handy, sometimes you can locate the offending ballcock by lifting up on the float ball while someone starts an offending faucet.

Another common cause is a faucet washer. If it only happens when using a certain faucet the faucet washer may be loose or damaged. This can cause it to flutter in the water stream causing the various sounds listed in the heading. Try tightening the screw the washer in the faucet stem. If the problem stops and later returns, mash the threads of the screw just a little with pliers so they bind in the stem when reassembled. If this doesn't work, then it's time for a new stem assembly.

Speaking of new valve stems, I've also had a third party replacement valve stem cause this problem. In my experience substitute faucet parts often don't work properly. Try to get replacement parts made by the manufacturer of your faucet. If you can't find the parts locally, they all have customer service 800 numbers, and sometimes they'll send you replacement parts free.

Speedy Jim also suggests, "Sometimes a worn out dishwasher/clothes washer solenoid fill valve can cause machinegun like, repeated hammering."  So, if the hammering happens while a washer is filling consider this possibility.

High water pressure can cause a variety of odd problems including these noises. High pressure can also damage toilet valves and other devices connected to the plumbing. If you're on a city water system, ask your neighbors if they are having similar problems.  If you have a well you probably have a water pressure meter. If you don't have one, borrow one or, buy one at the hardware store and check the pressure. If your pressure is above 60psi you may want to adjust your pressure reducer or install one.  [I understand some water systems have higher pressures in the main lines and pressure reducers between the main and your house, at the meter.  In this case, if the pressure regulator is defective you could have high pressure even if your neighbors don't. -- jim]

Sometimes pipe noises are caused by the pipes rubbing or bumping inside the walls because they aren't strapped down well or, because their stud pass-through holes are too small or off center. If this is the cause they've probably made the sounds since the house was built or, the wall was repaired.

This isn't very likely, but it may be a problem with the pressure regulator if:

  • your pounding sound happens while the water's running, 
  • it happens at more than one faucet, 
  • turning on other faucets changes the cadence, 
  • the pressure changes with the pounding, 
  • and, you have pressure regulator on your main water line 

While the noise is happening, check to see if it seems to be coming from the regulator.  If so, the regulator may need to be replaced.  



Water meters sometimes make a ticking sound that's transmitted by the pipe or water into the house. This ticking happens when, (and only when) water is running.

Sounds Like Running Water (Toilet) Off-And-On

If what you hear sounds like water running for a few seconds then quitting, and this repeats every so often (several minutes to several hours) -- the flush valve ( rubber flapper or ball ) in your toilet may be leaking.  Take the lid of the tank, put 25 drops of green or blue food coloring in the tank and come back in an hour or two.  I water in the bowl is colored your flapper (not the 1920s kind) is leaking.  If it turns out you need a new flapper Speedy Jim says the best toilet flapper is the red colored 'Bulls Eye' model by FluidMaster.   As you can tell, I have a lot of respect for Speedy Jim, a retired master plumber.

Here's an explanation of how a toilet flush works.

Other contributors who authored posts I used in compiling this article:

Robert Hancock
Paul Konigmacher

Some other names were lost -- my apologies.

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