Possible leak under the slab

Lets just start with, I have a leak somewhere. My water bill has jumped up considerably. I have old polybutylene pipes running to the house, but the leak doesn't seem to be coming from there. I have dealt with PB leaks in the yard and they are very easy to find... just look for the lake of water.

However, my concern is that my water meter is spinning and I can't find any trace of a leak inside or out of the house. The hot water levels seem normal, and I haven't found any warm spots on the floor that would indicate a hot water line leak. My toilets are not running constantly, and my faucets don't drip.

I also don't have a water cut off inside the house that will allow me to test and see if the meter keeps running with the inside water supply shut off. Does anyone have any suggestions for finding the leak assuming I have one under the slab?

Assuming there is a leak under the slab, would it be cheaper to dig it up and fix it, or to re-pipe the house through the attic and walls?

Any help or information would be appreciated.

A lack of visible water isn't evidence that there isn't a leak in the yard. First cut the water off at the house and see if the meter still runs. If it does then the leak is between the meter and the house. If it stops then it is under slab. If it is under slab then turn the water to the house on and the water heater off. If the meter still runs it is a cold water leak, if it stops it is a hot water leak. leave the water off a couple of minutes then open it quickly, if there is a leak you will har the water surge as the pressure equalizes (this is assuming no fixtures are leaking/dripping)

Fixing or rerouting is a judgement call. Does your area have a history of underground leaks? Sometimes you go through all the trouble and expense of isolating and exposing the leaking pipe just to discover that soil conditions or
inadaquate installation has corroded the pipe to near paper thin. Possible to repair but will leak again at another location shortly. How old is the house?
If it is under 10 years old fixing it may me worth it. Older than that you should just reroute, depending on the acidity of the soil.

leak

Professional leak detectors have multiple ways to pinpoint a leak besides ultrasonic detectors. But if you have PB piping under a concrete slab, that would be unusual, at least for any PB system I have ever seen.

Thanks for the info. The house is over the legal drinking age, 22yrs. The shut off valve in the house still allows a trickle of cold water through even when shut down as tight as possible. However, I made sure that nothing was running in the house as well, no faucets dripping, toilets running etc...

The meter was still running, I lost about 3 gallons in 30 min. according to the meter. Given that the shut off valve appears to be faulty, I still am not 100% sure that the leak is outside of the slab. The shut off valve is right under the water heater, which is just on the other side of the wall from where the water line enters the home. I am wondering if the leak might be under the slab, but before the shut off valve.

I will give your suggestions a try, though I suspect a cold water leak at the moment. We have had no loss of hot water, no warm spots under the slab, and the gas bill is about the same amount as it was this time last year.

Gotta love older houses. Coincidentally, the central AC died last month and has to be replaced. Its enough to make me want an apartment again .

There are companies with ultrasonic leak detectors. Absent the puddle or a hot spot, this is probably the only way to find it. PB is trouble, so a total repipe is worth considering. As an alternative to digging holes in your slab, it is not so costly and not so messy.

I can't say enough good things about these guys:

http://www.sleuthleakdetectives.com/

but of course it all depends on the guy who show up at your house. My guy said he could pinpoint an under-slab leak to within 2".

Where are you located? What's the length and path of the line between the meter and the shutoff valve?

Step one: replace the valve in the house. I don't know why anyone would put up with a leaking main valve. There's simply no excuse for it.

The water line runs about 100-150 ft from the street to the house, and just a few feet from there to the shut off valve. It runs across a relatively flat backyard.

As far as the shut off valve 'leaking' it isn't an external leak, it just doesn't seem to be stopping the supply into the house completely and I only recently discovered it. I doubt it is the cause of my problems, but it is annoying.

It appears to be a cold water leak. With the hot water off, the meter continues to run. The water line is pretty shallow in the back yard, maybe about 8 inches deep. I have had leaks back there before and they always have been very easy to spot. I suspect this is under the slab and that I will need to call a leak finder to come find it. I have lost about 100 gallons since this time yesterday.