When we built the kitchen, we installed a drain-pipe from the sink which just led away from the cabin a ways and drained onto the ground.  While this worked OK, it wasn't very attractive, so I dig a pit with my tractor and made a 'French drain' which is a hole filled with porus substrait. (in our case we used gray stones) The stones are large and irregular so that there is quite a bit void between them.  This void is where the grey-water from the sink flows.  The french drain is very effective and after almost 5 years has never backed up or stopped up. Plus the water helps to give moisture to Laurie's climbing roses.

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