How to Widen the Drain Pipe in a Vanity

Determine the size drain pipe you’d like to install in your vanity. You can install one that meets code or even use a 2-inch pipe.

Place the bucket under the trap in the vanity. Use the wrench to disconnect the trap from the drain body by turning the coupling nut until it comes loose. A coupling or slip nut connects the trap to a straight section of pipe, known as the trap arm. Disconnect that coupling nut and pull the trap free. The trap could be full of water, so place it in the bucket.

The trap arm connects to the stub out of the drainpipe that enters the wall. Disconnect the trap arm by loosening the coupling nut there with the wrench. Put it in the bucket and remove the bucket from under the vanity.

Measure the diameter of the drain body with the measuring tape. If it is 1 inch, you need a PVC enlarger that will connect a 1-inch pipe to a 1 ½-inch pipe. If you need to go out and purchase the enlarger, stuff the rag into the drain-pipe stub out. It will help keep the smell of the sewer out of your home while the drainpipe is disconnected.

Screw the PVC enlarger onto the drain body. Using a coupling nut and the wrench, attach the new trap to the PVC enlarger. Attach the trap arm to the drain trap. Remove the rag from the drain stub out, then connect the trap arm to it.