Toilet Drain

**Arky217** · 10-10-2012, 08:04 AM

Which of these is the best configuration for a toilet drain ?

Going to assume that C is incorrect because of no immediate vent pipe; that leaves A or B.
Which one would be the best configuration ?

Thanks,
Arky

hj · 10-10-2012, 10:24 AM

Deepending on the situation, all three can be correct, although "B" is the way it is usually done. It usually "boils down" to the logistics of the installion. The depth of the sewer and the direction from the toilet to the sewer connection, are two considerations which could change which one is "best" for a particular situation.

**Terry** · 10-10-2012, 10:39 AM

In Washington State none of those would work. Since the toilet connects to a waste stack, it needs a vent between the waste stack and the toilet. That vent would then extend through the roof.

**Arky217** · 10-10-2012, 03:22 PM

Originally Posted by Terry

In Washington State none of those would work. Since the toilet connects to a waste stack, it needs a vent between the waste stack and the toilet. That vent would then extend through the roof.

Sorry, I wasn't clear on the main stack; there is no upstairs, the main stack is the main vent.
With that being the case, would A or B be the better configuration ?

Thanks,
Arky

**jadnashua** · 10-10-2012, 03:43 PM

I'd go with B, there would be easier air exchange with the stack. But, I'm not a plumber! This is the more commonly installed configuration and it hides more of the pipes, giving more room underneath the sink, if you need it.

hj · 10-10-2012, 03:51 PM

quote; This is the more commonly installed configuration and it hides more of the pipes, giving more room underneath the sink, if you need it.

This is a TOILET, and I hope you do NOT use your sink in place of a toilet. AIr is a gas, so it is not governed by the same rules of flow as water. At various times I have installed all three configurations and a couple you do not show.

**jadnashua** · 10-11-2012, 01:57 AM

Was thinking sink...given a choice and enough room for it, then A may work better with a toilet, but dont' think it makes a big difference.

hj · 10-11-2012, 08:14 AM

quote; then A may work better with a toilet, but dont' think it makes a big difference.

They will all work exactly the same, with a slight caveat. Since a toilet is an "S" trap, the greater the drop out of the toilet before the vent connection, the more "suction" that will be created possibly helping the toilet flush better.

**Arky217** · 10-15-2012, 08:23 PM

In the following picture, assuming that the 'other drainage' pipe cannot be moved, which would be the better arrangement, A or B ?

Thanks,
Arky

**Terry** · 10-15-2012, 09:00 PM

I would use "A"
B isn't vented.
B would only work if it only included the same bathroom group (lav/shower) that the toilet is on and nothing else.

hj · 10-16-2012, 07:16 AM

"A" always works. It would depend on what the "other drainage" is whether "B" would be acceptable. I had a customer once, where the "other drainage" was the discharge from a small sewer pump. Every time it operated it sucked all the water out of the toilet. The only cure would have been to break into the structure and relocate the connection.

**Arky217** · 10-19-2012, 08:03 PM

One last time on the toilet drain.
Because of obstructions and space limitations, I need to have the toilet drain into the
stack lower than the tub and sink.
Would there be any potential problems with this arrangement, that is, having the sink and tub drain into the stack about a foot above the toilet inlet ?

Thanks,
Arky