Step 7 · Test for Leaks
The final and most important step is to test your work. Close the main tub drain and fill the bathtub with water. Continue filling until the water level rises above the bottom of the overflow cover plate, causing water to flow into the overflow drain. While the water is draining through the overflow, use a flashlight to look for any drips or moisture around the outside of the cover plate. If you do not have access behind the tub, check carefully around the plate on the inside of the tub. If you do have an access panel, open it and check for leaks on the overflow pipe itself.