Since moving into a new house, we've been battling with an issue with our washing machine. We've got it plumbed in beneath a sink (as the previous owners had done) as shown in the image below:

photo of plumbing

Above this image is the sink. The red box on the right of the image is where the drain from the washing machine enters the drain. Just above that is a black hose which is connected to the sink's overflow. The red box on the right is the problematic bit...

When we use the sink, this arrangement seems fine. Water drains quickly without any leaks. When we use the washing machine, however, we often find that there is water pooled on the floor. Having watched the washing machine during the "drain" part of its cycle, I found that the water was being forced up through the other arm of the "Y" (red box on the right).

As you can see in the image, I've applied some tape around the problematic fixture as temporary fix. Perhaps not surprisingly, this hasn't performed that well. In case it's relevant, the tape is covering a sort of tapered, stepped pipe. The sort that you might push a rubber hose onto.

One other thing I've tried is to detach the offending part from the "Y" and cap off the hole. From my local hardware store, I've purchased a range of "cap ends", but none of them seem to fit. I think I'd measured the wrong part - my measurements say 40mm dia, but both the 40mm or 32mm caps I purchased seem too large.

Finally, worth noting that I've detached the trap / "U" for inspection. It's not blocked or anything.

I'm now backing up a bit and wondering if I'm going about this all wrong. Is there a correct way to solve this problem?

  • First of all, it doesn't appear to me that the connection from the washer drain is properly connected to this mess at all. I don't see what prevents that from falling or being pushed out. Secondly, why is there an open "Y" here at all? This is a MESS!
    – jwh20
    May 29, 2021 at 11:56
  • 1
    If the leak is coming from second unused Y section, would replace the double Y with a single Y.
    – crip659
    May 29, 2021 at 12:01
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    You don't mention anything about the red box on the left...
    – JACK
    May 29, 2021 at 12:29
  • 2
    This is a dishwashing machine, yes? May 29, 2021 at 13:17
  • 2
    Washing machines need a 2" stand pipe, ~4' high. For a dishwasher you need a dishwasher tail piece (the kind with a little hose barb sticking out) and a hose clamp. And that no one has cut too much of the hose off at the end where you can cut it for different sizes. You say one of them is barbed, but it looks like an odd fitting and it's got too many inlets anyway. New tail piece time....
    – Mazura
    May 29, 2021 at 14:05


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