Drain into vent?

Giles · Sep 1, 2008

My son recently bought a home that has two baths upstairs and a toilet flange mounted in the basement. There has never been a toilet in the unfinished basement and there is only provisions for the toilet.
The flange is mounted about 3' from the main drain coming down from upstairs. Coming out of the floor behind the flange and close to the wall, is a 3" pipe that travels up to the upstairs floor where it is connected to the the 3" vent for the upstairs toilets.
I am sure this pipe coming out of the slab is a vent for the basement toilet. and my son wants to have a full bath consisting of a toilet a sink and a whirlpool tub.
We would like to add a couple of sanitaryTs, one over the other and just off the floor, to this vent. The runs will be as short as possible and all on same wall. Will this work?

Master Plumber 101 · Sep 1, 2008

Is this a new house with pvc or a older one with cast and galv. The 3" you see is very doubtful a vent for the water closet. It most likely is picking up waste from above. It can be used as a vent if it was used as a combanation waste and vent system, but again doubtful. Don't use san tee's to tie waste in, use wye's. Can you post a pic. with lay out, it could be more helpful.

Sponsor · 2022-01-29T12:20:58-0800

Redwood · Sep 1, 2008

You need to verify whether the line is a vent or a drain. Wet venting between floors is not permitted. Meaning if the line carries waste down from above it cannot be a vent.

I hope that makes more sense than the drivel posted above....

Giles · Sep 1, 2008

The 3" PVC pipe coming from the basement floor is definately connected to the main vent just above the toilet drains. I traced this 3" pipe and it goes to the attic and out the roof. nothing else is connected to this pipe. Tomarrow, I will try to post a picture.

hj · Sep 1, 2008

connections

And if he uses Y's or combination Y-1/8 bends into a vertical stack it WILL be wrong.

Redwood · Sep 1, 2008

Oh man the bad advice out of this guy is getting old!
The training the union offers in Wisconsin must be pretty lame...
Either that or, maybe he's a first year apprentice...

Master Plumber 101 · Sep 1, 2008

A few things, are we talking about adding a bathroom in the basement and connecting to the building drain. Most likely you have to open up concrete and expose piping. If that is a main vent for the building sewer than most likely the proper drainage fitting's were probably not used. You could however after using proper drainage fitting's use a wet vent system to vent all three fixture's. By the way don't listen to redwood as he is old and can't remember alot.

Redwood · Sep 1, 2008

Master Plumber 101 said:
A few things, are we talking about adding a bathroom in the basement and connecting to the building drain, or is this a bathroom addition on the first floor. hi, If you tie into a stack above the slab, what is your explanation why you can't use wye's vs tee's.

Ask your plumbing class instructor tommorrow!

Master Plumber 101 · Sep 1, 2008

Redwood is old and

so stay clear.

NHmaster · Sep 2, 2008

Redwood may indeed be old, but he is correct in that you can not wet vent between floors. Branch lines run to a vertical stack should be made with a sanitary tee, not a wye, or wye and 1/8 bend as their use can cause a siphon or s trap effect. If the 3" pipe is dry and connects to the vent pipe above the flood level rim of the uppermost fixtures it may be used to vent the basement bathroom group.

Master Plumber 101 · Sep 2, 2008

nhmaster said:
Redwood may indeed be old, but he is correct in that you can not wet vent between floors. Branch lines run to a vertical stack should be made with a sanitary tee, not a wye, or wye and 1/8 bend as their use can cause a siphon or s trap effect. If the 3" pipe is dry and connects to the vent pipe above the flood level rim of the uppermost fixtures it may be used to vent the basement bathroom group.

I'm not talking about individual line's connecting to a waste line with the vent on the top side of tee. I know you use san tee's for those connection's. I was refering to a building drain and using the correct fitting's for the tie in.

Redwood · Sep 2, 2008

Careful NH Master... This guy is a psycho!
He doesn't like being shown he's wrong...
Ya got him squirming...
He's trying to explain his way out...

Master Plumber 101 · Sep 2, 2008

Redwood said:
Careful NH Master... This guy is a psycho!
He doesn't like being shown he's wrong...
Ya got him squirming...
He's trying to explain his way out...

Dork! if I was squirming I would have left the fourm already. I'm here to stay. So keep slapping pip and I'll slap back.

Giles · Sep 2, 2008

nhmaster said:
Redwood may indeed be old, but he is correct in that you can not wet vent between floors. Branch lines run to a vertical stack should be made with a sanitary tee, not a wye, or wye and 1/8 bend as their use can cause a siphon or s trap effect. If the 3" pipe is dry and connects to the vent pipe above the flood level rim of the uppermost fixtures it may be used to vent the basement bathroom group.

I am still trying to post a picture but I am having problems. I will continue trying. I know someone would be able to steer me if a picture was posted.

Thanks to everyone for trying to help under these condition.

This pipe from the floor is "dry". It has a cleanout abour 12" off the slab. Considering and not totally understanding your quoted commint, I might add that this pipe is connected to the main vent 12" below the bath floor above. The vertical run from the tilets change to horizontal 18" below the floor. Will the revent need to be higher, like above the toilet water level? THANKS

Terry · Sep 2, 2008

Typical plumbing

NHmaster · Sep 2, 2008

I like that little drawing...gonna steal it.

Master Plumber 101 · Sep 2, 2008

Terry said:
Typical plumbing

Terry, just wondering why every thing is iindividually vented. Is that UPC code, or Washington state code?

Redwood · Sep 2, 2008

Washington is a UPC state.

Terry · Sep 2, 2008

just wondering why every thing is individually vented?

That drawing will meet code anywhere.
I could put up drawings that only pass in some cities, counties or townships, but I prefer to put something out that works every time for instructional purposes.

In Washington State until very recently, that is how we had to plumb.

Drain into vent?

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