Sink backup

[wizzy]

I have my own little drain cleaning business and I came across a plumbing problem I think. Not being a plumber I would like you experts to comfirm my thoughts on the problem. Customer had a friend replace basement sink in bathroom and hooked drain line from sink to just above trap for washer drain. So when customer runs washer on spin and water runs into drain pipe it can't handle the sudden flow and backs up into bathroom sink. I snaked washer line but problem is still there. I told customer that the sink should have it's own drain line and not T into washer drain line. Is that correct ? Thank you for your help.

[ToUtahNow]

I have my own little drain cleaning business and I came across a plumbing problem I think. Not being a plumber I would like you experts to comfirm my thoughts on the problem. Customer had a friend replace basement sink in bathroom and hooked drain line from sink to just above trap for washer drain. So when customer runs washer on spin and water runs into drain pipe it can't handle the sudden flow and backs up into bathroom sink. I snaked washer line but problem is still there. I told customer that the sink should have it's own drain line and not T into washer drain line. Is that correct ? Thank you for your help.


Wizzy,

I'm sure you're correct but you did not provide the information necessary to make the call with certainty.

Typically the flood rim of the lavatory sink is around 32” while the flood rim of the stand pipe might be as high as 40”. If you are dumping water into a 2” stand pipe the water will fill the sink before it will fill the stand pipe which will allow water to spill out of the sink.

Mark

[PLUMBER RICK]

wizzy, sounds like 2 fixtures on the same trap and possibly double trapping of the sink.

can you post a photo?

it's illegal to run 2 fixtures into the same trap. although you can have a 3 compartment sink into 1 trap, provided the trap is within 30'' of the sinks. this of course doesn't apply to your installation.

what needs to be done is a wye installed downstream of the laundry waste line. i would install it as far downstream of the laundry as possible to keep suds from coming up.

once again a photo would be very helpful.

rick.

[ToUtahNow]

Rick,

As this is a basement sink it sounds like a wye would mean you were jack hammering the floor. Then as far as the distance between sinks (30" not 24") to have the trap serve more than one fixture would require the sinks (not sink & stand pipe) were of similar depths. I'm sure there is nothing about the described installation which is legal.

Mark

[wizzy]

I like what you are saying Mark so I guess the easy fix would be to raise the hight of the sink. Rick I guess you could say the sink is double trapped as the sink had a trap and the wye from the sink comes in just above the trap on the stand pipe for the washer. They always had this problem but is worse now that they remodeled the bathroom and moved the new sink to a different wall. Maybe they the sink a little closer and a little lower. Thanks for all your help as it sure sounds like it wasn't a problem with my snaking of pipe but bad plumbing by a home owner.

[PLUMBER JAY]

wizzy
I don't think mark's solution was to raise the sink up highier. He was just explaining to you that you were right that the instal was incorrect.

If you do as Rick suggested by tying the sink into the laundry drain as far down stream after the trap as possible you should be ok. Like rick said use a wye and a 45 (at floor level) and rise up beside the stand pipe.

[plumbdog10]

Rick wrote: "it's illegal to run 2 fixtures in the same trap."

Not true. See section 1001.2 of the Uniform Plumbing Code.

[PLUMBER RICK]

dog, see section 1001.1, techniciality:p

as i was referring to his installation of a laundry standpipe and sink. i did mention the 3 compartment sink did not apply to his installation. and i was corrected on the 24'' to 30'' measurement.

rick.

[wizzy]

Ok Rick as I understand it now the rush of water coming down the stand pipe is hitting the trap and slowing down which causes it to backup into the standpipe and forcing it into the wye from the sink which is above the trap. So there is a fix and I will tell the home owner to have a plummer look at it.

[gitnerdun]

And here we have another excellent example of why homeowners should not have access to plumbing supplies.