I can hear water running in the walls behind my bathroom even when all fixtures are cut off. When I turn off the main cutoff, the sounds stops. When I turn it back on, the sound does not return immediately, but only after 10 min to 2 hours. There is a very small leak at the cold water cutoff under the sink. The sound of running water stops sometimes, it is not continuous. When the plumber came and I turned on the main water cutoff, the sound did not return immediately. They turned on the spigot on the outside and the sound returned and stopped when they turned it off, so they assumed it was a neighbor using my water and left. I had 2 small leaks repaired on an outside line out of that spigot, and the sound stopped for a few hours, then returned. I also have had some faucet repair in the bathroom, there is only about half the water pressure now in the cold water faucet after the repair. I do not have a water meter, the water is billed through homeowners dues. The house is on a slab, SW Florida, built in the 70's. I do not hear the sound in other walls so I feel it is related to that bathroom or the outside spigot. Any suggestions are greatly appreciated!