I have a 4" floor drain in a concrete slab. What's the easiest way to convert it for use as a sink drain? Does the sink need a trap since the floor drain has one? Thanks, Matt

Before you consider doing this connect you need to confirm that the 4" drain actually goes out to your sewer and not a sump pump. Are you on city sewer or septic?

Hi... I'm on a city sewer system and I have verified the drain connects to the sewer system. Thanks!

There is no way to convert it to a sink drain it is a floor drain and that is all. If you want a laundry or sink drain you have to run a new drain from below grade or from a adjacent stack assuming it is sized properly. In both cases a separate vent is required.

XLMP makes a very good point, (Welcome to The Plumbing Page at AMHD.) There's only one way you can do this without tearing up the slab and wall for the plumbing and run a vent out the roof and that is if you install the sink directly over the floor drain and use it as a indirect waste. And even then I don't know if it will pass code. Good luck, Tom