Late at night, our water pipes will start vibrating. It has nothing to do with running water as all water has been off for hours. I can go down in the basement and feel and hear the pipes vibrating. It never happens in the daytime.
I tried to run water when this happens, and the pipes still vibrate unchanged.
If I turn off the water main, the sound stops.
It comes and goes seemingly at random, gets louder and softer changes pitch.
I am hesitating to call a plumber because there is nothing to show during the day.
After spending two hours (and $200) with a plumber who checked everything in the house, we eventually tracked the problem down to a pressure reducing valve in the _city_ water main out in the street. The city came and made some adjustments and the problem is now gone. Don't know why it was just my house that was getting the vibes. Once we figured out what it was, we could stand in the street and hear it.