How to Connect a Kitchen Sink Drain Pipe

It’s rare for the drain assembly on a kitchen sink to fail and need repair, but if a sink is being replaced during a kitchen renovation or update project, part of the process often does involve installing a new drain assembly for the new sink.

The steps for installing the sink drain will depend on how different the new sink is from the old one, as well as what other components are being installed. For example, the new sink may have a different depth than the old one, so it may be necessary to perform some alterations to the branch drain pipe fitting entering the wall. Installation may be slightly more complicated if you are also installing a garbage disposal as part of the new sink installation.

Before You Begin

Kitchen drain traps are available in various bundled kits containing different configurations of parts to match specific situations—some for single-basin sinks, some for double-basin sinks, and some for sinks that will include a garbage disposal. Both chromed copper and PVC plastic drain trap kits are available; most people now use plastic parts for kitchen sink drains, which are generally hidden from view.

Kitchen drains are usually 1 1/2-inch in diameter, rather than the 1 1/4-inch pipes often found in bathroom sinks, so make sure you buy the right size. Occasionally, you may find a 2-inch kitchen drain outlet. If so, there are adapter fittings that can transition a 1 1/2-inch drain kit to the 2-inch outlet pipe.

Although many drain trap kits include flexible, corrugated tubing that makes installation much easier, professional plumbers generally do not use these, as the rough corrugations are quite susceptible to catching grease and food particles and causing clogs. It’s much better to use smooth pipes, cutting them precisely to size, to ensure a good flow of drain water.