The mysterious water pipe noise
Months ago, I noticed an odd, continuous wooshing noise in the basement. It seemed to come from behind the cabinet of shelves mounted above the washer. But behind those shelves is nothing. I puzzled over this for a while, got SJ to listen to it, and periodically would notice it and scratch my head.
Since we've come back from NZ, the noise is now audible in the living room, coming from the exact same area. It's gotten louder.
I scratched my head some more, and stared at the cabinet a bunch.
Eventually I noticed that the shelves themselves seemed to be making the noise. Sure enough, when I touched them, they were vibrating a bit, like a sound board. Resonating with what? With, it turns out, the water pipes. The copper water piping for the washer runs along & is attached to said cabinet. The pipes are carrying a fair bit of vibration.
Meanwhile, we can hear the noise in the bathroom too; I think the water pipes in the stack (i.e. in one of the bathroom walls) are using the walls as their sound board.
It sounds like... well... it sounds like a damped rumbling noise. It sounds like the dryer is running downstairs. A bit like water flowing through a pipe, or traffic in a tunnel. It sounds like an airplane passing overhead. It seems periodic, like a running engine of some kind.
There's not much in the house that could be generating the vibration. The fridge? The boiler? The heating? 24/7? Nope.
I think the resonance is coming in on the main water supply pipe. But what the heck is generating it? And how do I figure it out? And really, would all that ground it passes through not dampen it?