How deep to bury my new toilet drain pipe?

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WILLY TINKLER

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I am adding new bathroom in a building with concrete slab. cinder block walls and need advice on how deep to bury the 4" drain pipe coming out the back of the 8" thick foundation section footing the blocks rest on. The footings look over 30 inches deep..might be more but only went down 30". What is the minimum depth I can lay the pipe inside of the bathroom so I can know where to punch a hole in the footing to get it outside. The building runs a span of about 60 feet and the city main sewer is maybe another 20 feet away. I think the city sewer main is only 4 or 5 feet deep.
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Tuttles Revenge

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I would bury the pipe with at least 3" of crushed rock cover between the top of the pipe and the bottom of your slab. If the pipe is in or anywhere near the slab, it will crack along the run of the pipe.... So if you're pouring a 3" slab, 3" of separation and the pipe is roughly 3-4" and you put around 3" of gravel bedding under the pipe, you're digging 12" to the bottom of your trench and your pipe at that point before any slope, is around 7-8" below grade
 

Master Plumber Mark

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Soooo How far from the bore hole will the toilet flange be??? 5 foot... 50 foot??

Really All you need to do is be sure that their is some decent fall from the toilet flange
all the way across to the exit of the building....

Just put the toilet flange sitting into place and work downwards from there...
as long as their is some good fall you are good......

The drain really does not need to be flying
downwards, all that is necessary is putting a level on the pipe and the bubble goes
the right direction ... it will work, it has to work ...of course the more liberal the fall
the better .... but not necessary

Normally a toilet flange and a common 3 inch elbow is more than deep enough to work fine
and on occasion I have had to go with a 3 inch street elbow to ensure we had decent fall
out to the sewer....

It does not sound like you really are gonna have much of an issue
 

Reach4

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I would call your picture 8.5 inches deep, but I am not sure that is the convention. I suspect it is, because sometimes codes specify the amount of cover rather than trench depth.
 

Tuttles Revenge

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If 12" down works to get sufficient cover over your piping then that is a good spot to drill.
 

WILLY TINKLER

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I finally busted hole out and need advice on which fittings be best to connect to the 4" pipe coming out wall to make a 90 degree turn to main sewer Also how far from wall to put the 4" main line?
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wwhitney

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No opinion on the minimum distance the sewer line should be from the building as it runs parallel to it. Someone with more experience on that will hopefully chime in.

Your drawing looks like you are going to have an exterior vent on the outside of the building. If you aren't, you'd use a combo wye (long turn wye) horizontally to turn 90 degrees while providing a connection for the cleanout. Then a 45 (possibly street) on the barrel inlet so the cleanout extension angles up to grade.

If you are running a vent on the outside of the wall, then you would use a combo vertically (side entry vertical) for the vent takeoff, then a short section of pipe, then the same as the previous paragraph. If you want to minimize how far the second combo outlet is from the building, then instead of the vertical combo, you could use a street wye plus a street 45 on the branch inlet. That way the street wye can plug directly into the horizontal combo. [They don't make a street combo.]

Cheers, Wayne
 

wwhitney

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Yes, that's a combo, aka combo wye plus 45, aka long turn wye. You can get the same effect by using a wye with a street 45 into the branch inlet.

Cheers, Wayne
 

WILLY TINKLER

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Here is a few photos of pipe coming out of the hole I kn
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ocked out. The small pipe coming out is supply line coming from meter. How is best way to fill the oversized hole now in the concrete footing? Will mortar or sackrete damage the pipe? Does the combo wye 45 go on the the 4" pipe first and the other for the vent go towards the back end?
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