What causes water lines to vibrate when no water is being used, taps not being used?
It started 2 years ago, only when upstairs bath tub was being used, two days ago it started and vibrates 5 to 7 times an hour.. We may have a water leak behind the bar wall
Will take down wall next week.

Let's check for a leak, (without tearing out a wall). Since you haven't given me any details, (pump or city water I'll run them both down.
To check for a hidden leak on city water, shut off all water usage in the house and go out to the water meter. Check the little pointer. It should be absolutely still, no creep whatsoever. If it's moving then you have a leak.
If you're on a pump then make sure the pump's up to pressure and shut off water usage in the house. Turn the pump off at the breaker box and watch the pressure gage. If it falls back steady then you have a leak.
Let me know what you find. Good luck, Tom