Replacing a bathtub drain assembly is a common home maintenance task that directly impacts the functionality and appearance of the tub. The drain flange, which is the visible metal piece, is secured to the drain shoe below the tub, and a proper seal is necessary to prevent leaks into the subfloor. This process is manageable for the average homeowner and involves carefully removing the old components, preparing the surface, and installing the new drain with a reliable, watertight seal. A successful installation ensures the tub holds water and drains efficiently without causing damage to the surrounding structure.
Gathering Tools and Removing the Old Drain
You will need the new drain flange assembly, plumber’s putty or a rubber gasket, a rag, a cleaning solution, and a specialized drain removal tool, such as a drain key or a dumbbell-style wrench. These specialized tools are designed to grip the crossbars inside the drain without damaging the tub’s finish, which is a common risk when using improvised tools like pliers.
The first step is removing the old drain flange, which often requires significant torque due to corrosion or old sealant. Insert the drain removal tool into the crossbars and turn it counterclockwise, using a wrench or screwdriver for leverage if necessary. Once the old flange is removed, the drain opening must be cleaned to ensure the new sealant adheres properly. Use a rag and a cleaning solution to remove all traces of old plumber’s putty, soap scum, and mineral deposits from the tub surface around the opening.
Step-by-Step Drain Installation
Plumber’s putty is the traditional choice for sealing, and it should be rolled into a rope-like shape, approximately 1/4 to 1/2 inch thick, using your hands. Wrap this putty rope completely around the underside of the new drain flange’s lip, ensuring the ends meet to form a continuous ring.
It is important to apply the putty only to the underside of the flange lip, keeping it away from the threads, as the seal is created by compression against the tub surface, not by filling the threads. Carefully place the putty-coated flange into the drain opening and begin threading it into the drain shoe by hand. Starting by hand helps prevent cross-threading, which can damage the connection.
Once the flange is hand-tight, use the specialized drain tool to tighten it securely, applying steady, controlled pressure. As you tighten, the plumber’s putty will compress and squeeze out from under the flange. The goal is a snug fit that compresses the putty without overtightening, which could crack the tub’s enamel or damage the underlying drain shoe connection. Immediately after tightening, use a rag to wipe away the excess putty that has squeezed out from the perimeter of the flange.
Ensuring a Watertight Seal and Final Test
Plumber’s putty does not require a curing time, unlike silicone sealants, which may need 12 to 24 hours to fully set. This allows for an immediate water test, which is the most reliable way to check for leaks in the new assembly.
To perform the test, close the drain stopper and fill the tub with several inches of water, or up to the overflow plate if you are also testing the overflow assembly. Allow the water to sit for at least 10 to 15 minutes, which provides enough time for any small leaks to become apparent. The most direct way to check for a leak is to inspect the drain shoe connection from below, if there is an accessible panel behind the tub.
If no access is available, monitor the water level in the tub for any noticeable drop, and check the floor around the tub for signs of water seepage. If a leak is detected, the drain must be removed, the old putty cleaned off, and the installation process repeated with a fresh application of putty and careful attention to the tightening process.