It's a standpipe for a washing machine discharge. It could also have been
used as an illegal sump pump drain. Not a source of sewer backup but
certainly a source of sewer gas in the home since the trap is dry.
Where does the pipe from the top of the tee go? Does it vent out the roof
or is it the drain from a first floor fixture?
Erratum to last post:
I somehow missed the part of it being the main stack. I was looking at it
and thinking it was two inch.
It's definitely not code. It's probably an illegal sump pump drain. It
should be cut off and capped at the tee branch.
In 01/23/04 "Mark Monson" m email@example.com writes in part:
Come on Mark, there's not enough shown in the picture for you to make that
statement. From what is shown in the picture it looks like a perfectly legal
(in jurisdictions that use the Uniform Plumbing Code) installation for a
washing machine standpipe. However, there may be piping outside the scope of
the picture that would render the above statement incorrect
If there is an odor coming from it it is probably because the trap is dry as
posted earlier by someone else.
Speculation......however if it's not being used, caping it off would stop sewer
gas from escaping.
He said it was the main stack. You can't just tee off the main stack with
a P trap like that. Because the stack carries discharge from upstairs, a
standpipe like this would have to be separately vented.
However, there may be piping outside the scope of
On 01/23/04 "Mark Monson" m firstname.lastname@example.org write in part:
Go back and look at the picture. There is what appears to be a 3" cleanout tee
topped with a 3 x 2 reducer then a 2" sanitary tee. Would you call that a main
You are 100 percent correct on your last statement, I just don't think what is
shown in the picture is his main stack. That's why I said there's not enough
shown in the picture to fully answer the question as to what it is or if it
meets the code requirements.
At first glance it looks like two inch. That's what I thought too. But
look at the 3/4 copper next to it. With my handy dandy desk micrometer I
measure the standpipe at about 4.5 diameters of the copper service. 4.5 x
.875 O.D = 3.94" O.D.
It's four inch on bottom, three inch on top, with a three inch P trap.
First - thanks to both of you for looking at this.
I can confidently tell you that the main stack is the vertical pipe on the
left. It is 4" PVC. So is the P trap and the straight pipe with the open
This is a mess and I'm taking it out as soon as I get back up to my mother's
home in Syracuse - I live in Philadelphia. I don't think there's any rush
given that this has been in place for the 4 years she's lived there.
Or should I be thinking otherwise?
write in part:
looks like a 4 inch band,a 4inch c/o, a 4x3 bushing , 3 inch san
tee,with a 3 inch trap.cut it and cap it or pour mineral oil into the
trap it will not evaporate like water.( no sewer gas).but it will still
not be up to code.
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