Sink Drainage to old Washing Machine Standpipe

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TeeJay

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I need some good advice. A few years ago I moved a washer and dryer to another location so I could use the small utility room off the kitchen as a walk-in pantry instead. This room still has a water supply and the drain that was for the washer. I'd like to add a utility sink to this pantry but I'm not sure about connecting the drain to the old standpipe. I've opened the wall and can see the standpipe going into the concrete (the house is 35 years old) but don't see a P Trap. I assume it's under the floor. Is it possible to accomplish this?
I would really appreciate some help. Thanks all.
 

Tuttles Revenge

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A clothes washer shouldn't have had its trap under the floor where its inaccessible. I've seen a lot of clothes washers hooked up without traps, so that may just be a drain pipe. You will want to verify that it does or doesn't have a trap in the concrete.

double traps aren't allowed and will cause waste to slow down signifigantly and may cause back ups.
 

Jeff H Young

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Extremely unusual for me to see that unless its been hacked by a homeowner but an original house plumbed that way I've never seen that from the late 80s. Now Florida houses are a bit different exterior on a block wall perhaps ? So Verify before proceeding
 

Sylvan

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LOOK down the stand pipe and if you see water there is a great possibility of a trap there
 

TeeJay

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Thanks for all the feedback. I'm the original homeowner so I know there haven't been any changes since construction. It's an interior wall with a toilet on the other side of the wall. There is water at the bottom of the drain which means there IS a P Trap? Does that pretty much mean an end to my plans? I don't plan on proceeding if it means running new pipes.
 

Reach4

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If you are the original homeowner, you would know about the builder I presume. Regular house builder?

It seems possible that the standpipe was routed somewhere other than to the septic system.

Anyway, what I might do is to presume it is an untrapped line going to a good place. Then I would put a sanitary tee in, and put an AAV above that. 1-1/2 inch P-trap feeds into trap adapter in the side of the santee. Whether the pipe goes to the septic, city sewer, or a dry well, that seems like a reasonable action. I am not a pro.
 

Jeff H Young

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I'm not that familiar with your codes and traps below floor are something we never do here on a wash machine or a sink . can't say exactly the harm tieing into the standpipe would be but will refrain from recommending it , if it was tied into for a hand sink without double trapping and the top of standpipe left open it might be ok but I'm concerned trap could siphon , if it was out in garage or something I might try it on my own house definitely kinda shoddy though
 

TeeJay

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A clothes washer shouldn't have had its trap under the floor where its inaccessible. I've seen a lot of clothes washers hooked up without traps, so that may just be a drain pipe. You will want to verify that it does or doesn't have a trap in the concrete.

double traps aren't allowed and will cause waste to slow down signifigantly and may cause back ups.
Thanks for your post. I'm just taking shots in the dark here. I'm on a septic system. I don't detect an odor coming form the drain. Does that indicate a p trap? I also dumped water down the drain and then dropped a large nut on a string down the drain which indicated about an inch of water at the bottom. Does that indicate a p trap?

The builder, who was respected locally, put the foundation and roughed in plumbing in the wrong location and had to rip it all up to start over. He may have cut a few corners as a result but it seems unlikely this would be one of them. If there is a p trap it's definitely under the slab. There isn't one in the wall.

Thanks again.
 

John Gayewski

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Just run the drain into the standpipe receptor untrapped. Use an air gap. There's no problem with that.
 

John Gayewski

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Not sure how to apply that to a sink...the air gap. Thanks.
Cut the standpipe off at whatever height is convenient. Add add a reducer. Run your sink drain, at a height above the reducer, over and into into it.
 

TeeJay

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Cut the standpipe off at whatever height is convenient. Add add a reducer. Run your sink drain, at a height above the reducer, over and into into it.
Thanks, I understand that. One last question: I take it there's no need to vent?
 

Jeff H Young

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an airgap wouldn't be needed tying a sink into a standpipe? You could cut stand pipe to height 90 out wall 90 up and connect to sink tailpiece . kinda hokey but works , I'm sure you wouldn't pass code on new work , but might be legal or passed by an inspector . Trap below floor what would be considered a 2 or 3 foot tailpiece might fly?
If I was hired I wouldn't just put it in without explaining it could be code violation. I would not investigate normally to see if the washer was vented at a certain point an assumption is made, I don't know if everything plumbed on my home was done proper how could I didn't build it or inspect it
 

John Gayewski

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an airgap wouldn't be needed tying a sink into a standpipe? You could cut stand pipe to height 90 out wall 90 up and connect to sink tailpiece . kinda hokey but works , I'm sure you wouldn't pass code on new work , but might be legal or passed by an inspector . Trap below floor what would be considered a 2 or 3 foot tailpiece might fly?
If I was hired I wouldn't just put it in without explaining it could be code violation. I would not investigate normally to see if the washer was vented at a certain point an assumption is made, I don't know if everything plumbed on my home was done proper how could I didn't build it or inspect it
To run untrapped and vented into a receptor requires an air gap. Or at least I thought it did. UPC 801.2
 

John Gayewski

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So if the pipe exceeds 5 feet it needs a trap. If it exceeds 15 feet it needs a separate vent that doesn't tie into the sanitary vent system.
 

TeeJay

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So if the pipe exceeds 5 feet it needs a trap. If it exceeds 15 feet it needs a separate vent that doesn't tie into the sanitary vent system.
You guys are way over my head. I'm prepared to do as you suggested: run the sink to the standpipe without a trap, configured the way you described. Will it be OK? My main concern is that I'm not creating another problem by doing this. As long as everything drains properly, I'm happy.

And, as always, I'm grateful for all of the advice.
 

John Gayewski

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You guys are way over my head. I'm prepared to do as you suggested: run the sink to the standpipe without a trap, configured the way you described. Will it be OK? My main concern is that I'm not creating another problem by doing this. As long as everything drains properly, I'm happy.

And, as always, I'm grateful for all of the advice.
It will work fine and it is code. If you run more than 5 ft. of pipe it needs a trap that's all.
 

Jeff H Young

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Good Luck Tee Jay ! I think it will work fine , Id never intentionaly plumb this way and expect it to pass inspection on a job , but again see no real problem
 
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