I have a two story home with an upstairs master bath under renovation that currently only has an operating toilet (tub and sink pipes capped and shower valve off) and a downstairs bath with single sink, toilet and shower. I have a washer in laundry room and sink and dishwasher in kitchen. Refrigerator is not hooked up to water for ice. Garage has water heater (a few weeks old) and no other water or plumbing. This issue has been ongoing for nearly a year. When I stand in the downstairs laundry room, I can hear water movement behind the wall near washer. This area is about five feet from the outside water shutoff valve for the house. When I shut off the water at the outside valve, the sound inside stops. I have a T-foundation with a crawl space under the house. I've been everywhere under the house and there is no sign of water - everything, the ground, plastic tarping, insides of cement foundation - dry. Also, I have shut off everything in the house, including toilets, sinks, water heater and still hear the sound. I've checked the shower valves and they are dry as is the area around them. I am in a private park and we have our own water system, so I don't have a meter to check for water movement. I've put a glass against the wall and can hear it downstairs as mentioned before, and also upstairs, directly above where I hear it downstairs. It IS fainter upstairs, and there are no water pipes in that part of wall. As it is directly upstairs, my thought was it's the same stud bay and the sound was being telegraphed upwards. After more than six months, there is absolutely no indication anywhere of long term or even short term leakage. No wet or moist areas, no musty smell, no stained surfaces, no mold, no peeling paint. Nothing. This is driving me bonkers. Logic would dictate that if water is moving through the pipes, it must end up somewhere. If all outlets are closed, then the only logical conclusion would be it is exiting the pipes somewhere. But after almost a year of continuous leakage, there is no way it wouldn't have shown itself somewhere. The only place left is the shutoff valve itself, but when I shine a light down the six inch diameter access pipe and view it, it looks dry also. Any ideas guys? Thank you for reading this long paragraph - I hope I covered everything.

my initial thought is a bad toilet fill valve and a faulty stop. If the main stops the noise, but it still continues with just the individual stops off, then it stands to reason that there is a bad stop for one, and two, there is something that is allowing water to run slightly without any noticeable wet spots, unless of course it is full of water at all times. As you are already renovating, change out the supply stops with quarter turn stops first and foremost, then swap out the toilet fill valve and flapper because it is both prudent and convenient with the water off. Test for sound with the new stops turned off. If it is fixed, great, if not, cross that bridge when you get there.

Thanks for your reply KCRoto. I have a question or two from your reply. First, pardon my ignorance. When you talk of a faulty stop, are you meaning the water shutoff valves used for the sinks and toilets? If so, I'd think a bad stop for a sink would be obvious as it would have to leak to generate the sound of moving water, which none of them do. If it was a toilet stop, I could see it could keep a slow amount of water entering the toilet tank, but I've shut them off and drained the toilet tanks but still hear the water downstairs. The more I think on it, the more I suspect the main shutoff valve outside. If it had a slow leak on the house side of the valve, it might not be obvious, as it would soak into the ground below the valve and never enter the house. I will pull up the decking over the valve and take a much closer look. I'd love to hear your thoughts on my plan of attack.

unfortunately it sounds to me that you have a broken water service line between your outside service stop or well and where it comes up in the crawl space.

How old is the home and what kind of piping does it have?

Sorry - I forgot to mention that somehow. The house was built in 1978 and it is all copper piping....

We have water sound at all bathroom faucets, tubs, and toilets now unless water to house shut off completely. Our house was built in 1973 and has copper pipes. We cannot find any leak anywhere but noise continues near all these areas of two bathrooms unless water completely shut off to house. It isn't water heater pressure release valve problem, dishwasher, refrigerator, ice maker, kitchen sink, outdoor hose bib, washing machine problem. Husband says he has ruled out hot water problem but is at his witt's end figuring out what it is. I hope not slab leak as pipes in cement foundation. How do we find problem and fix it? Leak detector at water meter at street shows that leak detection dial moves very slowly. So we have leak. But how do we find where and how to get it fixd? Thanks for any replies with ideas.