Thread: Stand pipe oversized?

Dont know what they were trying to tell me with this setup. Washer drain is too powerful???? or maybe the drain is clogged and it takes awhile for the waste water to soak through the goop???

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Chris, I believe that oversize pipe is an attempt to prevent the overflow of water when the washer is emptying. That was probably caused by:
1. Partially blocked pipe somewhere down the line
2. Not enough pitch in drain pipe somewhere down the line
3. Insufficient vent pipe (too far away, undersized, or missing)
Difficult to determine exactly unless you can follow the drain, check clean outs for partial blockage, and check how far from the drain pipe venting is located. Of course, much of that is usually buried in the structure. A specialized camera made to insert in the drain pipe could answer these questions.
Curt Downs
Licensed HIC CT

The code calls for a 2" minimum drain. It doesn't mean that it can't be larger since most 2" lines dump into a 3" line quickly. If you are concerned about back up or improper venting then locate the nearest clean out, cycle the washer and check for overflow. Or cycle the washer as quickly as possible and see if there is backup. Cycle the washer and flush toilets, drain sinks or whatever to put additional water into the drainage system and this should indicate if there is stoppage somewhere.

It is never a good idea to go reduce the pipe size going down stream.

That drain line must have been for a sink at one time. No need for that trap on a washer, ( I don't think ? ), and that is probably what was causing the back-up.

I couldn't tell if the 3' pipe fed into a 2" pipe. You are correct that the 3" drain ashould not feed a 2" drain. As far as a trap is concerned. The code requires a trap if it feeds into the house drains. Some areas allow "gray water" disposal out onto the ground but most health departments in my area frown on it and I do also. Skeeter season doesn't need any help.

Originally Posted by Bill Scott

I couldn't tell if the 3' pipe fed into a 2" pipe. You are correct that the 3" drain ashould not feed a 2" drain. As far as a trap is concerned. The code requires a trap if it feeds into the house drains. Some areas allow "gray water" disposal out onto the ground but most health departments in my area frown on it and I do also. Skeeter season doesn't need any help.

Not doubting you at all Bill, but wondering where the trap is in a typical washer installation ? Usually there is a 2", ( 1 1/2 " ? ), 45o poking out or they're just flushed into the center of those plastic box like wall "kits" that also envelope the hot & cold water. Is the trap inside the wall / part of the rough-in ?

Originally Posted by Garry Blankenship

That drain line must have been for a sink at one time. No need for that trap on a washer, ( I don't think ? ), and that is probably what was causing the back-up.

Excuse me? "No need for a trap on a washer? Any drain connection needs a trap to prevent sewer gas entry into the living spaces.

Originally Posted by Garry Blankenship

Not doubting you at all Bill, but wondering where the trap is in a typical washer installation ? Usually there is a 2", ( 1 1/2 " ? ), 45o poking out or they're just flushed into the center of those plastic box like wall "kits" that also envelope the hot & cold water. Is the trap inside the wall / part of the rough-in ?

Yes, the trap is in the wall. The "washer box" is just to pretty things up and get the whole thing flush with the finish wall. Trap still required, you just can't see it.

Hi Chris,

Don't know where you're located, but here on the 'left coast' where we're on the UPC that set-up would be wrong (and maybe why they kept having clog/back-up problems ?)
For 804.1 - The 2"+ standpipe receptor is required to be >18" but <30" (IRC is <42", if that's what you're on)
-The trap must be >6" and <18" from the 'floor' (measured from weir portion) I'm assuming from your photo that they're using the 'interior' floor level, and not the concrete /garage floor level the washer is sitting on. (Even that would be a stretch, as that trap weir looks to be more than 18" from the top of that exposed gas curb/foundation section behind the CW)
- Also, based on the size of the 2" pipe, the trap seal height does appear to be too deep/excessive, with more than 4" from the weir level to the top dip.

All that, beside the fact that others have pointed out, the amount of water flooding into and filling that larger/longer receptor pipe doesn't stand much chance of draining properly through the 'reduced' 2" trap and drain pipe.

Steve L.

Originally Posted by Steve Lottatore

All that, beside the fact that others have pointed out, the amount of water flooding into and filling that larger/longer receptor pipe doesn't stand much chance of draining properly through the 'reduced' 2" trap and drain pipe.

Steve L.

And how is it any different than a washer hose emptying into a laundry sink? I always recommend installing a stand pipe, but the sink has worked well enough for generations.