How To Plumb A Bathroom Sink Drain Through The Floor

Plumbing a bathroom sink drain through the floor involves creating a hole in the floor and installing a drain pipe, allowing water to drain from the sink into the plumbing system below the floor. This guide will provide step-by-step instructions on how to complete this task, ensuring a functional and watertight drain system.

Materials Required

Before starting, gather the necessary materials:

Drill with hole saw (2-1/4 inch)
Drainpipe with P-trap (1-1/2 inch)
PVC cement and primer
Pipe fittings (couplings, elbows)
Washers and nuts
Caulk

Step 1: Determine Drain Location

Determine the optimal location for the drain hole by placing the sink over the proposed hole. Mark the center point of the drain hole on the floor.

Step 2: Create the Hole

Using a drill equipped with a 2-1/4 inch hole saw, drill a hole through the floor at the marked location. Be cautious not to drill into any underlying pipes or wires.

Step 3: Prepare the Drain Pipe

Assemble the drainpipe by connecting the P-trap to the drain outlet using a coupling. Extend the drainpipe by connecting additional pieces as needed to reach the hole in the floor.

Step 4: Install the Drain Pipe

Apply PVC cement to the pipe connections and carefully insert the drainpipe assembly into the hole in the floor. Ensure that the P-trap is positioned correctly to allow water to flow freely.

Step 5: Secure the Drain Pipe

Use washers and nuts to secure the drainpipe to the underside of the floor. Tighten the nuts securely, but avoid overtightening.

Step 6: Connect to Plumbing System

Connect the drainpipe to the plumbing system under the floor using appropriate pipe fittings, such as elbows and couplings. Ensure all connections are secure and watertight.

Step 7: Install Sink Drain

Install the sink drain assembly by connecting the pop-up drain to the drainpipe. Secure the drain with the locknut and washer.

Step 8: Test and Seal

Run water through the sink to test the drainage. Inspect for any leaks at the joints or connections. Apply caulk around the sink drain to provide a watertight seal.

Conclusion

By following these steps, you can successfully plumb a bathroom sink drain through the floor, ensuring proper drainage and preventing water leaks. Remember to always exercise caution when working with plumbing and electrical systems and consult a qualified professional if necessary.