I have a water pipe in my basement that runs off the main line to an outside spigot. It's only about four feet of pipe with a valve in the middle of it to restrict or allow water flow only to the outside spigot. When I turn the valve on to allow the water to flow to the spigot, but leave the outside spigot turned off, I can still hear constant running water in the pipe. No water seems to be leaking anywhere inside the basement from this short length of pipe. The outside spigot works fine if I turn it on but the running water sound from the pipe inside never stops. Only thing I can think of is the water is leaking in between the inside and outside walls, maybe? Any other ideas?

If u are sure the sound is coming from that pipe, shut off inside valve and replace pipe from inside valve to out side. Would install a new spigot on outside as well. Be sure pipe from inside is pitching down so spigot can be left open in winter to drain. This will keep pipe from cracking in winter from freezing water.

Chuck

It's possible there is a wall leak but at some point you would see water somewhere. Sounds travel a long way through piping, particularly if copper. I'd start looking for a toilet leak. Try shutting off the stop valve for each toilet, 1 at a time and listen for the noise to abate.