Been there. Done that. Only it was the kitchen floor we tore up.

If freezing isn't an issue, the plumber may be able to reroute the plumbing through the attic.

This may not be available in your location but there is a process to insert a liner inside the pipe: http://flow-liner.com/water-lining.html?gclid=CPr_v7Cf39QCFdSXfgodSPwGmw

The first thing I would do is try to isolate the location of the leak -- just to rule out leaky toilets, irrigation, etc.

Do you have PEX or copper pipe?

If it is indeed a leak under the slab, the issue I have is what caused it. Meaning - is this a one-off problem or is this a systemic problem (such as dezincification of brass fittings on PEX pipe, or thinwall copper at the end of its lifespan).

If it's a systemic problem, I'd go for a replumb through the attic.

I'm 90% sure it's copper pipe, at least that's what comes up to all the fixtures. Would not be surprised if it is deteriorating, that's nearly 40 years. Although the soil is alkaline so I would have thought it would not be corrosive.

How can you isolate the location? Listen with a stethoscope on the floor?

"Attic" is not what I'd call it...flat roof with maybe 12-16" between ceiling and roof, so square trusses, stuffed with insulation batts.

"Replumb", would this involve the entire house? Yikes. Just spent nearly $30k to have the roof replaced, slopes installed to prevent water pooling, and had to move gas lines off the roof. Would have been a perfect time to run new piping when the roof sheathing was off. Dangit.

Ugh, why couldn't they just put it right above the ceiling to begin with? Leaks would ruin the drywall but at least you could get to it quickly and without tearing up concrete.

The first thing I would do tox is see if there's a stop valve on main just before it go's under slab. If there is a stop,chances are good that it's a *%##@$ gate valve that either doesn't cut off 100% or doesn't move at all. At any rate I'd turn water off right at slab even if it mean's installing a new ball valve then look for meter movement. 50-50 chance the leak is between meter and slab. If there's yard facuets downstream from indoor plumbing I'd do some digging and investigating of those also. Hearing it indoors means nothing,I can hear my outdoor yard facuets well enough they sometimes remind me to turn them off when I go to bed. There are services that specialize in locating slab leaks for plumbers so the know where to bust slab or tunnel under. Good luck,sound's like you have a full summer with the ceiling and all to go along with this issue.

When my house was relatively new they had to repair a slab leak, and the contractor jack-hammered out the area and replaced the pipe. It was a lot of work, but covered by the home warranty.

Several years later we had a slab leak under the master bath tub, and they just rerouted the supply pipe through the wall and up to the ceiling. The house was in San Antonio, so freezing wasn't an issue as long as they wrapped insulation on the pipe. Routing it through the attic was much simpler than going into the slab.

The copper pipe running through my slab appeared to be sleeved properly, and there was no obvious problems during installation. However, I would never put pipes in the slab again. It would be much easier for long-term maintenance if I had a crawl space, or if they had run the pipes in the attic where they were more accessible.

Bruce

I tend to agree with you Bruce until I remember getting a call Chriatmas Eve morning for a water leak comeing from atic in Dallas. It was an old home that had water lines installed in atic when remodled. One those rare times temperature dropped to low teens in that part of the country. If occupants can handle a shut off and drain,overhead isn't a bad option. I'm wondering if Pex could be snaked through the limited space in the subject home.

I get a spike every year about now. Are you sure it's leaking? Turn off the faucets and look at the water meter. There's probably something in there that spins or wiggles to indicate even small amounts of flow. If that spinner is sitting still, then no leak.

You can bet that the rest of the pipe is shot if one area is. I would first get the city in-ground shut off valve turned off by the city. Then I would discuss with them the process of replacing the shut off valve and all of the supply line to the house. Most likely reroute a different way into the house than under the slab.

Vith said;

"#1.You can bet that the rest of the pipe is shot if one area is.#2. I would first get the city in-ground shut off valve turned off by the city.#3. Then I would discuss with them the process of replacing the shut off valve and all of the supply line to the house. #4 Most likely reroute a different way into the house than under the slab."

Vith what are you trying to do?. #1. We don't even know where the leak is,much less what caused it. #2. in every case I've seen the city cut off is "BEFORE THE METER". #3.Why should tox become involved with how public utilities handle replacement of their system? And when did it become the city's responsibility to replace service line on private property? #4 fall's under the cart before horses category. I'm sorry but this man is faced with enough without us hatching issues that are simply unreasonable..

The water line on your property is yours, not the city's. The meter in your house is theirs but the water line is not until you hit city property. So the water line under the house is the homeowners. The in ground shutoff is theirs (usually on their property either the sidewalk or the street), but if im going to trench a new line it would be nice to have a new shut off, but not completely necessary if not an option the city will do.

I saw that 'pipe liner' product used on an episode of This Old House on a home in New Orleans. It was a drain pipe under a slab. Though the process is not cheap, it compares favorably with trenching and slab busting. It can also be used on 1/2" copper lines in walls or underground.

OP:

If you are still dealing with this issue - please look again at my original post.

You need to understand if this is a system wide issue. If it is system wide, meaning that the plumbing is at the end of its life, you need to re-plumb and the only practical way of doing that is through the attic and side walls. Your flat roof will make this much more difficult. The good news is you can do it with PEX and fish some of the lines into place.

You can consider pipe lining -- but if you have copper pipe that has reached end of life - I'd question how long of a fix that would be. It would be something to ask about if you go that direction.

Copper plumbing has a lifespan of 50-70 years so 40 years is a little short if it was properly installed unless it was thinwall copper. Ground chemistry, water chemistry, even electrical currents, etc can shorten the lifespan.

You may be able to see what type of copper -- K, L or M -- was installed if you can find a length of expose pipe with the printing on it. If it's type M - that's the thinnest type and I'd say you are at the end of life.

Pardon the pun,lineing the network of 1/2" pipe beneath slab is a pipe dream. Even lineing sewer pipe is possible only if there is no branch between start and finish points of liner. Making it fartur difficult (think impossible) is turning short radius 90* turns in pipe. Then there's the fact that every single loop above slab would have to be un-soldered. It isn't going to happen.