My current sink plumbing looks like this with a single waste inlet. enter image description here

When I remove the current single waste inlet, the connector looks like this: enter image description here

I bought one of these (the connector is 40mm):

enter image description here

Is it wierd this has a hole in it? enter image description here

But my problem is both the dual waste inlet and the sink trap have a female connector so I can't connect them.

What part should I buy?

Thank you

Trap from different angle. enter image description here

  • 1
    Your trap is too deep. Can you include a photo from a different angle, so we can see where the drain goes after the elbow above the trap? With this configuration, the trap will contain a massive amount of water as described in this image. With this much water in the trap, the drain will tend to drain slowly, and will be prone to clogging.
    – Tester101
    Commented Apr 9, 2016 at 15:46
  • Are you saying the left part of the trap is too high?
    – Dan
    Commented Apr 9, 2016 at 19:42
  • 1
    Yes, that's exactly what I'm saying.
    – Tester101
    Commented Apr 9, 2016 at 21:30
  • 1
    The trap is actually assembled incorrectly, I'm assuming to make room for the wye. This image shows where the parts should go.
    – Tester101
    Commented Apr 10, 2016 at 1:55
  • @Tester101 Thank for you help. I added a new photo of the trap from a different angle, it has some crazy piping going on.
    – Dan
    Commented Apr 11, 2016 at 19:53

1 Answer 1


The part you have is for connecting to the top of a standpipe trap. Not for adapting a existing single-spigot P trap. The hole at the top is for air admittance I think.

What part should I buy?

I would buy a "Washing Machine Trap with Double Spigot"

enter image description here

Example: McAlpine WM11 £10 ish.

Since your waste connection is quite high this might mean adjusting the other plumbing.

  • So I have bought the wrong part?
    – Dan
    Commented Apr 9, 2016 at 14:49
  • 1
    @Dan, Yes. I'd take it back for a refund (I've done that many times). Commented Apr 9, 2016 at 14:51
  • @RedGrittyBrick why is one of them pointing upwards and the other one downwards? Should I have some kind of special consideration on the height of the appliances?
    – zom-pro
    Commented Feb 17, 2020 at 20:33
  • @zom-pro: They swivel through 360 degrees to any position that is convenient for the connection. Commented Feb 17, 2020 at 22:37

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