Dishwasher plumbing - high loop causing occasional leak

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Hhussey

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Hello!

I have two questions.
A.) I had a leak from my dishwasher years ago, but it seemed like a one-time thing and my husband at the time didn't know why it leaked. But this morning I heard a backup sound from the plumbing under my sink and water was in the cabinet under my sink and on the floor. Also, I went downstairs to my unfinished basement, and there was a ton of water down the wall. Also, I noticed the exposed wood (ceiling of the basement), beneath the dishwasher and kitchen sink had some water damage. This leads me to believe the dishwasher has been leaking more than I realize.

When I looked at the plumbing under my kitchen sink I realized that the high loop goes into a cut-off ABS pipe and I think the water is backing up and flowing over. Is there a plumbing solution I can do to make this overflow not happen? I am a DIYer, but if this is a job for a plumber please let me know.

B.) Does this connection look correct?

Thanks so much,
Heather

IMG_8289.jpg
 

Terry

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Some locations use a standpipe for the dishwasher. If it's overflowing, it may be that the sink line is backing up. It might need snaking. What happens when you fill both sink bowls and then drain them?

Sometimes instead of an open standpipe, they use an insert fitting, threaded into a 1.5" x 3/4" FIP fitting, keeping everything tight.

Or sometimes the high loop goes into the disposer, after the plug inside the disposer has been knocked out.
 

WorthFlorida

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You'll need to just run the dishwasher and look at it while it is draining. It's hard to tell from the picture but the trap arm for the dishwasher has a 90º bend to the tee in the wall. Technically, the trap arm has to be 2 pipe diameters. It appears to be a 1.5" pipe, therefore, 3" is all that is needed to the tee. That 90º maybe causing too much restriction, or could be plugged some and causing a slow drain.
 

Reach4

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How accessible is that drain line in the basement? Doing something down there may be your best way to clear the drain line. If you can see the drain line from the kitchen going down into the basement floor, I have some comments as to how you might clean that.

However running the dishwasher to the disposal has its advantages. In that case, a slow drain pipe below would cause backing up into the sink, rather than overflowing into the cabinet bottom and beyond.

The term "high loop" does not apply to what you have. You have a standpipe (A). I don't know what B is. It seems unrelated to the dishwasher. Right?

Your white pipe is more sloped than usual, but that is not causing a problem.

What is your question mark in the photo referring to? The black nut?
 
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John Gayewski

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It looks like someone glued abs to pvc which is also suspicious for a leak. I think id figure out exactly what's leaking and why before I did anything.
 
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