The hissing faucets, banging water pipes, and screeching showers that go with noisy plumbing are annoyances, and can indicate a need for repairs or adjustment. In order to diagnose them, the first thing to do is to figure out if they come from the inlet side (when water is turned on) or from the drain side (when water is leaving the system).
The cause of drain noises is usually related to poorly designed plumbing drain system layout. The causes of inlet side plumbing noises, however, could be any of a number of different problems, such as worn faucet or valve parts, excessive water pressure, appliances or pumps that have been incorrectly connected, improperly placed piping connections, and other problems.
Inlet Side Noises
Hissing: If you are hearing hissing noises when faucets are opened even slightly, then excessive water pressure is usually the cause. Consult our page on pressure-reducing valves for what to do for this kind of noisy pipes.
Thudding: A jarring thud sound heard when a faucet or appliance is shut off, typically followed by shuddering pipes, is also known as water hammer. This condition is created when a pressure wave reverberates through the system, caused by the reverberation of water which suddenly has no where to go forward.
Water hammer can also happen if a valve is opened which drains water into a restricted section piping. Water hammer thuds can be gotten rid of by installing a device called a water hammer arrestor; these are air chambers or shock absorbers fitted to specific areas in the piping where the problem is occurring. Water hammer arrestors allow the shock wave of the stopped flow of water to dissipate in a compressible portion of air.
On some older plumbing systems, short, capped vertical sections of pipe are installed on faucet runs which are intended to fulfill the same function. The vertical pipe is supposed to have air in it to dissipate the pressure wave, although over time they can fill with water, leading to water hammer. In this case, it is sufficient to completely drain the plumbing system of water to restore their function. To do this, turn off the main water supply valve, open all faucets, then re-open the main water supply valve and shut off all faucets one by one, starting with the faucet closest to the supply valve and ending up with the faucet furthest from it.
Screeching/Chattering: Loud screeching or chattering noises when a faucet or valve is opened, which stops when the faucet or valve is fully opened, indicates loose or damaged components inside the fixture. The best way to eliminate the noise is to replace the faucet or valve completely with a new one.
It is also possible for noises like this to happen in appliances such as pumps, dishwashers and washing machines. This happens when the appliance is connected improperly to the plumbing system and then transfer internal motor noise/vibration to the piping. To isolate vibrations in appliances, always connect them to the system using plastic or rubber hoses, rather than rigid piping.
Creaking/Scratching/Tapping/Squeaking: When you hear these kinds of plumbing noises, it is usually due to the contraction or expansion of copper hot water pipes. The sounds are coming from the pipes sliding along loose fasteners or adjacent house framing as thermal changes in the pipes, heated by the water passing through them, occur. To eliminate the noises, you will have to pinpoint them by ear.
If you follow the sounds while they are happening, you will likely find a pipe hanger bracket that is loose or a pipe hanging in close proximity to a floor joist where the pipe is rubbing. The problem can then be stopped by attaching some foam pipe insulation around the pipe at the contact point. You can also add additional support to the pipe in the form of fastening strap brackets to nearby structural framing members.
Drain Side Plumbing Noises
When addressing residential drain pipe noise, you are mostly looking to insulate pipes in order to muffle unavoidable layout-related noises and to reduce or get rid of surfaces on which falling or rushing water can strike.
In existing houses, it is too late, but for new construction or renovations, resilient underlayment should be used to support shower stalls, bathtubs, wall mounted sinks, toilets etc. in order to dampen sound transmission.
Especially implacable noises come from drainpipes which are not running vertically to the basement or which branch off to horizontal runs of pipe supported at joists of other framing. Drain pipes are large, so that they transmit lots of vibration, and they transport large volumes of water. Cast iron pipes are the quietest material for drain-vent-soil system runs, due to their large mass; use them in any renovation or replacement of plumbing.
Walls containing drainpipes can be soundproofed with sound-insulating wallboard and fiberboard or double paneling. Unfortunately, such measures are not always completely successful; a poorly designed drain layout can be tolerated, but never cured of noise altogether.