View Full Version : Finding the main drain line under a slab

11-04-2006, 04:51 PM
Project is building a shower where none is. Imagine a clock. The proposed shower drain will be in the center. Its 8 ft or so from the toilet at 12:00, 5 feet from lavatory also at 12 :00. 7 foot from the washer drain at 8:30, 6 foot from the kitchen sink at 2:30, I must be close! The cleanout is 11 foot away at 6:00. If there was a device I could send into the cleanout that makes noise, I would know where to cut the slab.... Or do I need to estimate and start cutting? How is this done? Does the main drain pipe ususally enter the house straight in from the cleanout and then tee to various locations? Or is every house drained differently depending on the mood of the designer? House built in 69, St Pete florida, block and slab. Cleanout is in back of house, city sewer.

master plumber mark
11-05-2006, 04:36 AM
I could not get a good idea of where or what you are doing but
it all sounds pretty tight inside a small house...
(havent had my coffe yet)

if you are planning on tearing up this flooor, I hope you arent
living in the place while this event is going on....

I have seen the results of fellows trying to tear up their slab homes
while the family was still living inside ....LOL...

one fellow started to trench out a new sewer line for another bathroom
and he hit and cut a water line and a heat run stopped him dead in his tracks.
with piles of mud and concrete everywhere and a large trench going
through the living room of the house........
with plywood planlks laying over the mud hole.... he., he, he

needless to say it was impossible to do
and he had a great big muddy mess
on his hands...

in a smal area like that, you are probably
going to have to take a good guess and go for it.

this isnt a neat or precice science here
and you need lots of room to work too....

I would find the center spot that lines up the best in between
the toilet run and the main clean out on the outdside of the home...
and make a probe type hole.....

try not to hit water lines, or play with heat runs, hopefully they
are overhead...

11-05-2006, 07:30 AM
Hire someone with drain camera equipment. The camere end also has a locator transmitter on it. A hand-held probe allows you to pinpoint the location of the camera end point.

11-05-2006, 11:41 AM
Or they make underground cable locators, Fisher makes a good one, you clamp the transmitter on one end of the cable (the ground wire works fine) and they you take the receiver over the area and it beeps like a metal detector. For your wire, you could use an electrical snake. You should be able to rent this thingie at a good rental company. It'll get you withing 6-12".