Source
r/HomeImprovement•
postmeat

Dishwasher drain loop

I recently purchased a house and am getting a new dishwasher. I took a look at the old drain hookup under the sink and thought it looked a little weird. (Photo) After some googling, it looks like this is an attempt at a "high drain loop." I read that for a high drain loop the drain hose should go as high as possible (to the underside of the counter if possible), but mine is only raised a few inches. I also noticed that it connects to the sink drain after the P trap, which I think is wrong. I don't know what the duct tape is doing either, but it looks like an extra tube is coming out for some reason? The house was built in the 1960s.

My question is: do I need to change anything here before installing my new dishwasher? If so, what are my options?

Posted Sep 23, 2021, 5:51 PM UTC

36
ArtBaco•

Redo the sink tail pipe and p-trap. The dishwasher hose should be before the p trap. Also, raise the drain line so it is as high as possible. It should not be allowed to sag, as it does now. New dishwashers use an "air gap" to prevent backflow. If you buy such a dishwasher, you or a contractor will need to drill a hole in your countertop to install it.

3
festerwl•

A little unorthodox but I see what they were trying to accomplish.

As long as there is water in the drain hose at the bottom it's acting as a trap.

If you're concerned watch it while it's draining. When the pump shuts off you should see the water settle back into the clear drain hose. Theoretically all of that water to get suctioned into the main drain but with a smaller pipe into the larger I'd bet that would be highly unlikely.

My bigger question is what's up with the random duct taped part?

3
[deleted]•

Replace tailpiece with a dishwasher tailpiece, get a threaded plug for the current spot that copper pipe contraption is sticking in. Should be fairly straightforward.

3
Jeff_Session•

Before you get cutting you may want to look into an air gap attachment.

1
dominus_aranearum•

You already have a high loop in your dishwasher drain. The hose is coming from the top of the cabinet, right? The pump for your dishwasher is at the bottom. The odd setup with the flex hose going down and back up before the copper is actually creating an s-trap. While not code, it effectively works.

To correct this, replace your sink drain tailpiece with one that has a dishwasher drain inlet. Hook your new dishwasher drain line into it after the high loop or into an air gap which then goes to the tailpiece drain. Remove the copper and plug the tee-wye.

1
Itisd•

I don't know what they tried to do, it looks like they tried to cobble together a dishwasher wye.

I would just redo the whole drain. Get a proper dishwasher wye and put it on sink side of the p trap.

Also, ensure that the drain loop goes right up to the bottom surface of the counter top, as high as you can get it.

1