How to determine if I have a slab leak or not?

Question

What are some good ways to test if I have a leak in the slab?  I have a property under contract, and there is some cracking/heaving in the kitchen tiles. See picture below:

[img]http://imgur.com/onlolXF[/img]

When you knock on it, it makes a hollow sound on the tiles that are cracked.   I brought in 2 contractors to look at it and they both said it’s just the tiles which need to be replaced. They were confident it wasn’t a slab leak.

However, being a newbie, I am still concerned and want to be 100% sure (or as close as possible) that it is or isn’t a slab leak.  I called a few plumbing companies and they quoted me at least a couple hundred to come out and do a pressure test. I’d rather not pay so much if I don’t have to.

Thanks!

Steve Babiak · Answer

That seems unusual to me (at least in my area it is).  How does the water bill get allocated?  Is usage info tracked and available for audit purposes?  Who gets stuck paying for the water "lost" due to the foundation cracks affecting the water supply line, resulting in leaks?

Rick Bradd · Answer

Bryce, I just had another slab leak fixed, this is the third one, in my primary. Here is what the plumber and I did to see if we had a leak, check the house that every single valve is turned off, even the toilets, washer etc.

Check the water meter and write down the number.
Wait 30 minutes
Check the meter again, if it went up, you probably have a leak.

The plumber had a listening tool and thought he found the leak, it was wrong. So we called a company called Pinpoint Leak detection, they were able to find the exact spot and we did a bypass.

I wish I had called them first, would have saved me some money in the long run.

Also, I was able to hear the leak when I listened carefully, that is what first clued me in.

Good luck!
Rick

Jason Grote · Answer

Bryce Y. I think the test you are needing is a hydrostatic test of the sewer plumbing correct?  All of the posts in this thread are referring to a supply line leak test.  Typically, slab issues from a plumbing leak are the sewer line leaking over time.  The two ways that it can be tested is with a sewer camera or a hydrostatic test.

If you just have a couple of hollow sounding tiles, that is not a good indicator of a sewer line leak under the slab.  If you can see an obvious "heave" in the middle of the house, then you should be alarmed.  Many foundation repair companies will come out for free to shoot levels.  This is what I would do if I wanted to be sure.  If the slab is level, then no worries...

Bryce Y. · Answer

Carlos F. haha I am definitely learning a lot so whatever gray hairs will be worth it.  I just wish I had scheduled closing to be sooner.  Too much waiting is making me anxious

Carlos Flores · Answer

I was going to email you to see how you were coming along, Brice.  Sounds like you're going to have gray hair by the time you get to closing.  HA j/k.

Bryce Y. · Answer

Steve Babiak

Currently the water bill is just divided by four and the landlord pays.    It comes out to about 150/month.  I have no idea what happens if there's a leak or if I get audited.  I'd  love to submeter at least my 4-plex but I think it'd be too expensive.

Chris Masons
Are you sure this is possible if all 4-plexes are on 1 meter?  I don't think there are individual meters for each unit.

I'm really on the fence about getting the test done.  The more I think about it, the more I'm leaning towards not getting it done...

Chris Masons · Answer

Bryce,

NO need to turn off the water meter at the supply if you can go into all the apartments and make sure all fixtures are turned off and no  water is coming out...

At thsi point go take a look at your water meter and see if the smallest dial in the middle is moving - with all fixtures off and no water running that dial should NOT be moving. If you see it moving that tells you water is runnng somewhere.

This may be tough to coordinate on a 4plex but certainly not impossible.

Chances are you don't have a slab leak and it is just cracked tiles.

thx and good luck,
Chris

Bryce Y. · Answer

Chris Bounds Rick Bradd

Thanks for replying.  This is for a rental.  I should have mentioned earlier the property is actually a 4-plex.  This cracked tile problem is only visible in one unit. There are no other signs of foundation problems.

As far as turning off the water meter, I can't do that since this 4-plex sits on a lot with 3 other 4-plexes, and all 16 units are on one water meter.

I will try listening for the leak, though I don't feel confident in my abilities to diagnose this problem very well.  Thanks.

Chris Bounds · Answer

Bryce, you can get a foundation inspector (different than a repairman) to check it out.  They cost around $200-300, but they will give you an unbiased engineers report of the foundation condition.  If work needs to be done they will let you know what specifically.  They will come back to inspect the completed work and sign off on it for a small fee.

If you are looking to flip the property then the foundation report will be useful to have for the end buyer's bank conditions.

That being said, I have a few loose tiles in my personal home that make a hollow sound and I'm certain I do not have foundation problems.

Bryce Y. · Answer

Sorry not sure how to get the image to come up.

How to determine if I have a slab leak or not?

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