I'm replacing some waste pipes and drainage and need to know what is the best way to fit the waste pipes (from washing machine and sink) into the hopper / gully. The hopper I am using looks like this:

back inlet hopper

It seems there are two ways I can get the waste pipes into the hopper:

1) Through the black plastic top. The solid part (over the shallow end of the hopper) has two circles marked on it. I assume I can drill these out and stick pipes in. The pipework would be visible this way.

2) The side and back inlets (two of which are visible in the picture). Again, I assume I can drill these out and stick pipes in. The pipework would be hidden underground this way, which I would prefer.

Is there any disadvantage with either of these approaches? If I use the underground approach how should I seal the pipes into the hopper? Or am I not supposed to use the underground inlets for this purpose?

1 Answer 1


I'm assuming this is for storm/rain water runoff and now sewage waste. For a location that freezes in the winter I've seen the recommendation to run the above ground gutters to an air gap and then to the top of a catch basin (hopper) like yours. This allows the melting ice to run off if the ground below is still frozen. If drain is already below ground, or you don't experience significant freezing in your climate, then using the below ground ports should be fine. These side ports tend to be designed to easily knock out, either with a gentle push, or at most with a hammer and screwdriver.

  • To clarify my situation, the waste pipes are coming from a sink and washing machine. My property is quite old and doesn't have separate storm and foul drains.
    – Eborbob
    Oct 22, 2015 at 22:29
  • Sounds like what we'd refer to as a gray water drain. I'm less familiar with the requirements for those, and local codes may vary for the other side of the pond.
    – BMitch
    Oct 23, 2015 at 6:55
  • The side ports seem to be about 57mm diameter, which doesn't match any standard waste pipes I've seen. How should the pipes be secured into the hole?
    – Eborbob
    Oct 23, 2015 at 11:08
  • That sounds like the inner diameter to connect to a 3" PVC drainage pipe. For the storm water stuff I'm used to, it's a loose fit, especially when connected to corrugated piping. I don't know how much, if any, of this applies to gray water systems.
    – BMitch
    Oct 23, 2015 at 15:19

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