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 alt.home.repair.
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.
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 alt.home.repair
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
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
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
This isn't very likely, but it may be a problem with the pressure
- 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 alt.home.repair contributors who authored posts I used in compiling this article:
Some other names were lost -- my apologies.