How to Install Drain Pipe Under Bathroom Sink: Step-by-Step Guide

A clogged or slow-draining bathroom sink can disrupt daily routines, but installing a drain pipe under the sink is a manageable DIY project. With the right tools and simple steps, you can restore functional drainage and avoid future plumbing headaches.

Begin by shutting off the water supply and draining the sink completely. Use a pipe wrench to remove the old trap and clean the sink flange area. Measure and cut the new drain pipe to fit, ensuring a snug seal. Apply pipe thread sealant to the threads, insert the pipe into the flange, and secure it with slip nuts on both ends. Connect the drain to the P-trap, then test for leaks by restoring water flow. For optimal performance, slope the pipe slightly toward the main drain to encourage drainage.

Gather a pipe wrench, adjustable wrench, PVC primer and cement (if using plastic pipe), slip nuts, P-trap, drain flange, pipe thread sealant, a pipe cutter or hacksaw, and a flashlight for hard-to-see areas. Having the right materials ensures a leak-free, long-lasting installation.

Avoid overtightening fittings, which can crack pipes; always clean flanges thoroughly; and never skip the pipe sealant—this prevents slow leaks. Also, ensure proper slope; a pipe that’s too flat or steeply angled may cause drainage issues. Taking time to measure twice prevents costly rework.

Installing a drain pipe under your bathroom sink doesn’t have to be intimidating. With careful planning, the right tools, and attention to detail, you can complete the job efficiently and safely. For added peace of mind, consider checking local plumbing codes or consulting a pro for complex setups—your home’s drainage system will thank you.

This video shows how to assemble drain pipes under a sink. If you are looking for an easy step-by-step instructional on how to plumb a drain, then this is it! In this DIY plumbing tutorial, I'll show you how to install the sink drain, namely the P trap.

If you also want to see how I installed my wall faucet and vessel sink, watch the video above. There are 3 parts you'll need when installing a new sink drain: a P Trap kit, a trap adapter, and a pop-up (or regular) sink drain assembly. Expert advice on how to install or replace a bathroom sink's drain, including images, a tutorial, and a helpful DIY video.

In this step-by-step guide, learn how to replace the pipes under your bathroom sink and fix any leaks for improved plumbing performance. A step-by-step guide for installing a kitchen or bathroom sink drainPutting in a sink drain is a simple home improvement project that anyone can complete in less than half an hour. First, decide whether you'll be installing your new drain.

1. Install Pop-Up Drain (s) This guide assumes that you have already purchased your sink bowl (s) and have existing wall plumbing in place. Regardless of location, all sink plumbing will connect to a drain in the sink bowl.

For bathrooms, we recommend Oatey pop-up drains, which can be installed according to these instructions. Follow these easy steps to install a new bathroom sink drain. Learn what tools you need, how much time it will take, and the cost of installing a sink drain.

If you have a bathroom sink with an overflow outlet you need to opt for a drain assembly with an overflow opening to make sure the sink functions properly. Once you have determined whether you need a drain assembly with an overflow or not, now you can pick the material of the sink drain. Learn how to handle under.

In this episode of Repair and Replace, Stephany shows how to replace a drain in a bathroom sink. Does your sink have a pop-up drain?