Any sound is a result of vibrations, the frequency and intensity of the vibration determines what sound is generated. Water “whizzes” past and thru sharp edges, elbows, and rough pipe walls, and thru valves having small passages. The turbulence in the water causes the vibrations and makes noise. Just like “white water” (no, not a Bill Clinton scandal), but the turbulence of flow. Vibration from turbulence resonates through the pipe and surrounding materials, and that makes sound. When pipes touch the wall, the wall board acts like a speaker! The pipe travels through the building making noise any opportunity it has (touching wall board, studs, or anything that conducts vibration).
The minimum pipe size used (as per code), strapped as per code, isn’t always done according to the code’s intent (or sometimes not done at all), and banging occurs. Isolation of piping requires skill, tools, isolators, and testing. The optimum is not sought after by many, compounded by the fact that lots of buildings move as they age, and the slight shift may allow the pipe to have direct wood contact.
Sometimes water velocities increase, and a noise develops, long after code has been complied with! For example, a pressure regulator “all of a sudden”- wears out from water erosion and chlorine (after 20 years - is that all of a sudden?). The failed regulator lets more pressure through, and bada-boom - pressure makes velocity, and that makes noise!
If a plumbing fixture is added after the original piping is sized, you can have an undersized pipe branch making noise.
Copper itself is not the quietest pipe material! Conduction of sound from a faucet noise can travel a long way. Valve noise can travel from the pressure regulator at the home’s inlet to the upstairs master bedroom bath!
Poor grade valves in retail grade “priced-to-sell” fixtures can be noisy. It is the size and shape of the casting and valves in the faucet itself that can make the noise.
Shut off “stops” under sinks are also a very noisy problem. The velocity inside is very high and washers often get loose and chatter when water whizzes past at 30 ft. per second (proper velocity is 1.5 ft. to. to 10 ft. per second, NOT 20 or 30 ft. per sec.)
Old multi-turn valves can get a loose washer causing a shuttering or rapid banging when used. Whistling and humming are also caused by high velocity water vibrating the plumbing. See my “Plumbing stories” for a real twist on that!
Pipe banging is caused by the sudden stoppage of water within the pipes. Fast moving water caries a good amount of inertia. When a valve closes suddenly (and ¼ turn valves can close very quickly), the energy of the water coming to a sudden stop causes a “water hammer.”
Noise from underground landscaping irrigation can travel into the building! Often sprinklers in the yard are not pressure regulated (so that the system can get away with fewer control valves). I find 20 ft. per sec. very common in landscape sprinklers; however, code specifies the max flow rate is 10 ft. per sec. for PVC. That high velocity, vibration, and water hammer effect can all cause: you guessed it, noise!
Waste water can also cause noises, and is governed by the same physics.
If you have noisy pipes, give me a call. It may be a symptom of a more serious issue. Early diagnosis can prevent more serious and expensive damage that could result if left unchecked.
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