For the past few I weeks we noticed a hissing noise behind our bathroom walls, as if water is running somewhere. Due to my busy schedule, just this weekend I began to troubleshoot the suspected leak. I turned off all the valves inside the house (faucets, dishwasher, toilets, washer, water heater etc.) and made sure all the water spigot and sprinklers outside was closed. The hissing sound was still present. So I looked around the inside and outside of the house for visual leaks. Nothing except for a wetness on the ground by the exterior wall of the house. I proceeded to dig about a foot of dirt. As I dug the hole, water very slowly fills the hole but I could not see where it's coming from. I noticed the water in the hole only fills up to about 2 inches below the surface so it's not actually flooding, however, it enough to make the ground wet. As I dig another foot of dirt in close proximity of the first hole, the same thing is happening. I'm suspecting a slab leak. Can anyone comment? I made an appointment for a plumber this coming Weds. This is something new to me. It's just weird how the water do not fill the hole completely as if there is a concentration of water inside the walls like how the toilet bowl goes back to the original level after a flush. I hope the plumber knows what he's doing and give me an accurate assessment. By the way, I also closed the main water valve to the house and that stopped the sound so I know it's in my end of the water line and no visible leak inside the house. Thanks for any input!!

the only input i have is either you or someone you pay find the leak/ leaks. then either you or someone you pay fix the leak/ leaks.

The hissing noise unfortunately sounds like a under-slab leak, even from here. You can try to determine if it's a H or C line by shutting off the water heater. Locating it could be tricky and sometimes an outside locating company needs to be brought in to pinpoint it.

e-plumber
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"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

Sounds like a failed joint above the floor, turn off the hot water heater water inlet valve, listen to see if the hissing subsides, If it does then you know it is a hot water line, if not then close the main valve, if the hissing stops then you know it is a cold line that is leaking, Since you can hear it in the house with the NAKED EAR, it is most likely above ground level.

PlumbCat TM 2003


Plumbermandan



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water seeks its own level. meaning the water fills the hole only as high as the saturated ground will let it unless the leak is in the hole and is exposed.

from what you have posted you have a slab foundation and thus the water pipes are ran underneath it and turn up through it. it would not be uncommon for the leak to actually be in the concrete where the original plumbers didnt protect the copper from the concrete well enough. if it is close enough to the surface you will hear the leak with no visual evidence of it on the floor. it is either a pretty good size leak, been going for a while or is close to the outside of your house for it to show up as a wetness on the ground.

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PLUMBERS "Protecting The Health Of The Nation"

Turn off the water valve to the water heater and the leak will probably also stop. If so, and there are no hot spots on the floor, then a leak locator, and possibly a call to your homeowner's insurance company, may be necessary before the plumber.



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Underfloor leaks transmit through the piping very well, thank you. Above the floor leaks usually result in a wet floor which they do not seem to have.

if it is behind the tub the water will leak through the opening made for the waste and overflow. in slab floors they usually form out the area where the drain is.

Thanks to all the inputs. Yesterday the leak detector and plumber came to work on the leak. It turned out my suspicion was correct. It was a slab leak on the cold side. It took 1/2 an hour for the detector to find the vacinity of the leak and another 6 hours to actually find, repair and cover up the leak by the plumber. Considering the leak was beneath the wall, there was not a lot of damaged done to access the leak. Just a few tiles (as of this morning). I called the insurance as hj suggested and they will cover everything including the tiles minus my deductable and the price to fix the pipe. So I'm glad about that. I did not realize it cost that much to fix but I'm glad it's done with.
As for the cause of the leak. The plumber said it could be that when the builder layed the slab, instead of filling fine sands around the piping like it should have been, they filled it with rocks that eventually rubbed against the pipe and made a small hole. Although the pipes was covered with a blue sleeves the rocks still cut through it. By the way, I watched the plumber dug up all the rocks beneath the slab. Also, in my observation of the piece of pipe that caused the leak, it seems more of a poor workmanship issue that caused it. The leak was located on a bend (L shape) and the actual hole is inside the bend were I noticed on both sides of the hole is a dimple which probably weakened the 3/4 copper K pipe. I'm no plumber but with proper tools I've done cleaner bends than that. The house is just over 8 years old and I just hope that was the only one (wishful thinking). Thanks again!!

8 years old and a slab leak, unbelievable...
More Plumbers need to know how to make clean bends in soft copper, without tools.

It seems that this sort of problem is common.

Thanks for taking the time to post back the results, you're one of the few that does.

e-plumber
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"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

it is not always the plumbers fault. concrete workers are notorious for breaking and bending plumbing as they prepare for and pour the concrete.

in your case it was not the rocks that cause the hole but the kink in the copper. i seriously doubt that rocks will rub a hole unless you have huge amounts of ground movement which would also lead to foundation problems

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PLUMBERS "Protecting The Health Of The Nation"

Once again, thanks for the input. After this slab leak incident to our home, I have been actively getting all the information I can about house foundations and plumbings as I have no idea how they work. This website defenitely gives me a lot of insight.
May be in the future when this happens again, which I'm convinced a big possibility, I'm able to tackle the repair myself. I watched the plumber from start to finish and in my opinion, I'm confident I can do the job myself. Granted I have to hire a leak detector. Although the insurance is partialy paying for the bill, it will at least save me the deductable. I can't see making another insurance claim and coming up with the deductible when this happens again. Eventually the insurance company will either raise my premium or drop my policy.
dlh: the master plumber, who worked on the leak, mentioned something about the foundation of our home was among the toughest cement he had dig up because he damaged two bits (for drilling) and the ground underneath was also among the densed because inspite of all the rocks, a big puddle of water still acumulating on the bottom after shutting the water for atleast 20 hours. So, I hope that's a positive sign as far as the foundation issues. Likewise, I'm doubtful about the rocks rubbing as I see no evidence of any scratches around the hole that caused the leak but then again what do I know about pipes.
e-plumber: is it my understanding from your last comment that typically when plumbers install the pipings on the foundation they bend the copper tubings by hand? That's another insight I learned from this website...

What usually happens is that the installer tries to make too sharp of a bend and kinks the tubing. Then rather than throw it away and get a new piece he tries to straighten it out. Eventually the kink acts as a hinge and expansion/contraction finally causes a leak. It is more common on hot water pipes because the degree of expansion/contraction is higher because of the greater temperature change. I will find a hundred hot water leaks to every one cold water one.

hmmm i have seen a lot more cold leaks than hot. it isnt the contraction and expansion that causes a leak at the kink. it is turbulence that the kink creates.

well for 1 you had water leaking for how long? if it has been going for a while which it probably was before it got big enough to hear above the floor. the ground was saturated in that area and 48 hrs. would not have dried it out.

being a leak under the slab did your plumber use soft solder (comes in a roll) or did he braze the pipe (comes in sticks)? soldering is much easier than brazing but is not allowed under a slab in all areas i know of. brazing will get the pipe red hot and you do not use flux. he may have made it look easy but trust me there is more to it than meets the eye. but you can save money by uncovering the leak yourself.

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PLUMBERS "Protecting The Health Of The Nation"