Plumbing leak strange scenario

[xlr8ngn]

This is in a commercial metal building. There is a significant water leak as the water bills are outrageous. The supply is 3/4 copper pipe. There is no water visible outside anywhere and the ground is very dry.

I believe I found roughly where the leak is under the concrete slab. I cut the water on, and I can hear water leaking into the 4" PVC sewer pipe through an unused and plugged toilet sweep. My theory is the water line is next to the sewer, and the leak washed a hole in the side of the PVC pipe and that is where the water is escaping. I shut the water off and added compressed air to the system and I can hear air leaking into the sewer. I do know sound can travel a very long way through a pipe.

My question is should I get someone with a sewer camera to explore and find exactly where the leak is so I don't go cutting a bunch of holes in the concrete floor? Is my above theory plausible? I have checked every toilet, sink, water fountain there is and I fully believe it is under the slab.

 

[Medic1957]

Sounds like a good plan. Probably save some headaches in the long run.

 

[xlr8ngn]

Where is your water METER in relationship to your water main SHUT-OFF VALVE ? Does your water meter continue to count up (or turn) even if your water shut-off valve is turned off, or no ?

You should be able to WATCH the meter turn (or count up) with all your sinks, toilets, fountains, faucets turned off and no one using water AND your water main VALVE turned on, this will verify your theory that you have a leak under the slab.. somewhere .

With all fixtures turned off and toilets not being used the meter is still turning, rapidly. There is only a shutoff at the meter and none in the building.

 

[BHJ]

If you video the sewer, All you will know is where there is a defect in the sewer pipe and you wont find out where the water service is leaking. Yes the water will follow the path of the least resistance which is probably the sewer ditch, but it may be leaking and following the sewer pipe many feet from the point that it is actually infiltrating into the sewer defect.

I'm kinda skeptical it's an all copper service because copper is a very sturdy material for a water service and usually doesn't leak unless physically damaged or at a failed connection of some sort like a union.
As far as finding the leak If you are going to do it yourself then use a stethoscope (geophones even better) or see if you can get a glass and put it on the slab and then put your ear on it using it like a stethoscope to pinpoint your leak.
Good luck

 

[mountainmoped]

Back in the 1950s and 1960s many homes in Florida had copper plumbing. The failure of this copper pipe/tubing has kept plumbers in work for years. I don't know if is is something in the water or the soil but all of this copper plumbing eventually fails causing leaks, Rather than breaking up the concrete slab new CPVC pipe or Pex pope is run thru the attic. My first wife's father had a plumbing and electrical contracting business and I often helped them on these jobs.
http://www.repairmyleak.com/about/failure-copper.htm

 

[tlt092187]

leak locator and a bull saw

 

[MacTavish]

All this talk about running water makes me want to go run some water myself.

 

[Horsehat]

Water can run a long way under a slab.

 

[jbi1104]

This is in a commercial metal building. There is a significant water leak as the water bills are outrageous. The supply is 3/4 copper pipe. There is no water visible outside anywhere and the ground is very dry.

I believe I found roughly where the leak is under the concrete slab. I cut the water on, and I can hear water leaking into the 4" PVC sewer pipe through an unused and plugged toilet sweep. My theory is the water line is next to the sewer, and the leak washed a hole in the side of the PVC pipe and that is where the water is escaping. I shut the water off and added compressed air to the system and I can hear air leaking into the sewer. I do know sound can travel a very long way through a pipe.

My question is should I get someone with a sewer camera to explore and find exactly where the leak is so I don't go cutting a bunch of holes in the concrete floor? Is my above theory plausible? I have checked every toilet, sink, water fountain there is and I fully believe it is under the slab.

Call an experienced Plumber in your area. We love when people have theories as that usually means we get to fix the original problem,plus the theories.

 

[DADI03]

Probably a P-trap primer. Not sure how they work exactly (I do concrete) but I know when they set drains now they run a water line to them. The problem is if you have a drain that never gets water to it the P-trap will dry up and let the methane gas back into the building. So the fix was to run a water pipe that somehow lets water into it. Just a thought but who knows. But I don't think that running water could eat a hole into the side of a pipe like that. I think scoping it would be the way to go.