# Locating Waste Pipe Under Concrete Slab



## nap (Dec 4, 2007)

> Specifically, can I use a metal detector to find/trace the line? I figure the drain line has to be 6"-12" below the surface, right? 4"-6" slab, maybe more, and then some dirt. Any thoughts about using a metal detector, like those sold at Radio Shack? Has anyone ever done this before? Any other options or methods?


 if the pipe is iron, it is a good chance you could use a good metal detector. If it isn't, you can run a metal fish tape or snake into the pipe and track that but that takes an even better metal detector. If you have a friend with a metal detector, it would be best to try this without buying your own. I have had some good and some bad luck using a metal detector depending on the equipment and the variable involved.





> Has anyone ever used one of these pipe locators? Seems hokey to me, but the reviews, on the linked site and elsewhere, are mixed, leaning towards positive. Any experiences?


a dousing rod. Never had much faith in dousing. I have a friend that swears by it and claimed to be really good at it until I asked him to find a line for me and he was waaaaayyyy off.


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## stubits (Dec 30, 2008)

Thanks so much, nice to know it is even remotely possible. Pipe is definitely 3" cast iron, so hopefully I will be in good shape. What constitutes a "good" metal detector? Any recommendations?

Thanks!


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## Gladerunner (Mar 9, 2010)

Run hot water down known drain and look for pipe with infared hand held thermometer


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## nap (Dec 4, 2007)

just a guy said:


> Run hot water down known drain and look for pipe with infared hand held thermometer


not a bad idea. Since I am an electrician, we usually don't run water down our pipes so I hadn't even thought of that.


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## Alan (Apr 12, 2006)

stubits said:


> I figure the drain line has to be 6"-12" below the surface, right? 4"-6" slab, maybe more, and then some dirt. A


hopefully, but not necessarily. It could be quit a bit deeper than that.


P.S. GREAT IDEA above on the infared, but i'm not completely sold that you would transfer enough heat from the water by the time it reached the end. It would be interesting to give it a shot.


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## stubits (Dec 30, 2008)

The infrared thermometer sounds like an excellent idea. Some amount of the heat should transfer.

Alan, I am pretty sure it is not all that deep. I've pulled the toilet before and it doesn't go that deep. 

Anyway, seems to be worth a shot at least. I might pickup a thermometer from Harbor Freight just to give it a shot. They've got a good return policy.


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