My dishwasher is not draining properly and while taking a look at things I realized that the drain hose is not tied into the garbage disposal. Is this incorrect? Are there certain benefits for having it this way?

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3 Answers 3


If you connect it to the garburator, any backups fill the sink, rather than the cabinet under the sink.

  • Also any solids not ground up by the dishwasher macerator can be finished off by the disposal.
    – mikes
    Nov 14, 2017 at 21:48

I would say that failure to drain would be an internal fault in the dishwasher and nothing to do with the type of drain present. This is the first time I have seen a reference to a separate drain for a dishwasher. Could it be that this separate drain was originally for a clothes washer?

Disposers have a port for connection of dishwater waste water. I have always thought that this was for the convenience of not having to separately plumb a dishwasher into the drain above the trap. There are tailpieces with a side arm to accept the dishwasher waste and these are the standard connection if there is no disposer.

  • The advantage of the connection through a disposer as that the the disposer acts as the air gap. If you connect to a sink drain tail piece via a side arm fitting then you will need a counter level air gap in the dishwasher drain line path,
    – Michael Karas
    Nov 14, 2017 at 16:32
  • @MichaelKaras If the dishwasher connects to the sink tailpiece, the sink is the air gap (assuming the tailpiece is before the trap). If you're connecting below the sink trap, the dishwasher drain will need an air gap and a trap.
    – Tester101
    Nov 14, 2017 at 16:58
  • In the area I live various cities disagree what they allow, the stupid one of which requires disposal AND counter level airgap. In that city the only other option for dishwasher drain is 4' standpipe or sink discharge. The city next to that says a disposer is an air-gape. In this case there are apparently, correct or not, multiple interpretations of the code. Ask your local building office.
    – Tyson
    Nov 14, 2017 at 17:36
  • It was definitely not used for a clothes washer. It looks like it was purposefully set up like this. I'm just not sure why now.
    – Programmer
    Nov 15, 2017 at 22:09

It is recommended to connect the dishwasher discharge drain into the disposal for this very reason. Food will eventually get trapped in the dishwasher drain when it does you experienced this problem of your dishwasher not working properly. However if you were to connect the dishwasher discharge drain directly to the disposal and loop the hose high up underneath the counter and experienced a blockage it wouldn't go back down to your dishwasher, but it it would land in the disposal.

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