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Drain line from dishwasher is leaking when the garbage disposal is turned on? Answered

So occasionally when we turn on the garbage disposal there's a PVC pipe in the cabinet under the sink where the drain line from the dishwasher feeds into that will spew water out all over the floor of the sink cabinet.

It seems like it mainly happens when we hit the garbage disposal while the dishwasher is running. The sink will sometimes have water in it - but not full. This last time it was filled about 1/3 of the way with water. Other times it's had even less.

Are we just not supposed to run the disposal when the dishwasher is running? Or could it just be a clogged pipe that we need to run a snake through?

Thanks in advance for your help. :)


Using both at the same time produces too much effluent for your sewage line to dispel so it backs up.

It's not clear from your description but the root cause probably depends on whether your dishwasher drain runs through your disposal or if they have separate waste pipe connections.

There are several possibilities, you may be overloading your waste pipe if the washer is dumping water at the same time your disposal is forcing it through. Combine that with a loose or improperly installed fitting and you could have some spray.

If they are separate then the only other thing I can think of is vibration from the disposal is causing a loose connection to work free enough to spray.

Regardless of what is causing it there is some sort of bad fitting or pipe that needs replaced. This should be addressed sooner rather than later to make sure you don't end up with a mold or mildew problem.

The dishwasher does not run through the disposal. The disposal pipes connect with the other side of the sink's pipe and then goes into the wall. The dishwasher pipe connects to this, right before it goes into the wall.

The hose from the dishwasher is just a small ridged white hose that manually feeds into PVC pipe. About 1 foot of it goes all the way into the PVC pipe. I assume this should be secured in a better way?

That connection is probably your issue, especially if that's where the water is coming out. Take some photos and then show them to someone in the plumbing section of a local hardware store (honestly the smaller the better. Big box store employees don't tend to be as knowledgeable). They should be able to point you to some solutions for sealing that off.