How to Replace a Bathtub Waste and Overflow Drain Assembly

Begin by preparing your work area to prevent damage and streamline the process. Lay down an old towel or a drop cloth inside the bathtub to protect the surface from dropped tools. Open the access panel behind the tub and place a bucket directly under the drain pipes to catch any residual water. Unpack your new bathtub waste and overflow drain assembly kit and lay out all the new parts and required tools so they are easily accessible.

Start the disassembly process from inside the tub. Use a Phillips or flathead screwdriver, depending on the screw type, to remove the two screws holding the overflow cover plate. Once the screws are out, gently pull the plate away from the tub wall. The trip-lever stopper and its connected linkage assembly will come out with it. Carefully maneuver the entire assembly out of the overflow pipe opening and set it aside.

This can be the most challenging step. The drain flange in the bottom of the tub must be unscrewed counter-clockwise. The best tool for this is a drain key (also called a dumbbell wrench), which slots perfectly into the crosshairs of the drain. If you don't have a drain key, you can insert the handles of a sturdy pair of needle-nose pliers into the drain opening, spanning the crosshairs. Then, place the shaft of a large screwdriver between the plier handles and use it as a lever to turn the entire assembly counter-clockwise. This may require significant force.

Through the access panel, locate the slip nuts connecting the old pipe assembly. There will be one connecting the overflow tube to the overflow elbow, one connecting the waste shoe to the waste tee, and one connecting the bottom of the waste tee to the house's main drain pipe. Use channel-lock pliers to turn these nuts counter-clockwise and loosen them. Once they are all loose, you can wiggle the entire assembly free and remove it through the access panel. Be ready to catch any remaining water in your bucket.

A clean surface is crucial for a watertight seal. Use a plastic putty knife to carefully scrape away all the old plumber's putty from the tub surface around the main drain opening. Also, clean the area around the overflow hole, removing any residue from the old gasket. Once the bulk of the old material is removed, use a rag, potentially dampened with a little rubbing alcohol, to wipe the surfaces completely clean and dry.

Before using any sealants, test-fit the new assembly. Loosely connect the new overflow tube, waste tee, and drain shoe. Hold the entire assembly in place behind the tub, aligning the overflow elbow with the overflow hole and the drain shoe with the drain hole. Check the alignment of the waste tee outlet with the sanitary drain pipe. If the pipes are too long, mark the correct length and trim them with a hacksaw or tubing cutter. This step is critical to ensure all parts line up without stress.

Begin by installing the drain shoe. Place its thick rubber gasket onto the top of the shoe and position it firmly against the underside of the tub's drain hole. From inside the tub, take a small amount of plumber's putty and roll it into a continuous rope, about 1/4-inch thick. Apply this rope to the underside of the new drain flange. Thread the flange into the drain shoe and tighten it down with a drain key until it is snug and the excess putty squeezes out. Next, install the overflow. Place the beveled rubber gasket over the overflow elbow, ensuring the tapered side faces the tub. Press the elbow against the back of the overflow opening and hold it there while you attach the new overflow plate from the front with its screws. Do not install the trip-lever linkage yet.

With the main components secured to the tub, connect the pipes. Attach the overflow tube between the overflow elbow and the top inlet of the waste tee. Thread the slip nuts and gaskets and tighten them by hand, followed by a final quarter-turn with channel-lock pliers. Connect the waste tee to the drain shoe in the same manner. Finally, connect the outlet of the waste tee to the house's sanitary drain line, ensuring the slip nut is tight. Once the pipes are connected, insert the new trip-lever linkage through the overflow plate, adjusting its length according to the manufacturer's instructions to ensure the stopper opens and closes correctly.

This is the final and most important check. Close the tub drain using the new trip-lever. Fill the tub with 3-4 inches of water, ensuring the water level is above the overflow opening gasket. With the access panel still open, use a flashlight and a dry paper towel to inspect every new connection for drips: the drain flange underside, the overflow gasket, and every slip nut joint. Let the water sit for 10-15 minutes. Afterwards, open the drain and inspect the connections again as the water flows out. If any leak is found, gently tighten the corresponding connection. If it persists, you may need to disassemble and re-seat that specific connection.