Problems with a leaky bathtub are often traced to the overflow tube or overflow drain assembly. The overflow tube is a safety feature that channels water that has overfilled the tub back down into the drain pipes before it can spill over the edge of the tub. But if the fittings on the overflow tube become loose, it can allow water to spill out and drip beneath the tub, where it might even ruin the floor or the ceiling in the room below the tub.
When a tub leak appears, often the impulse is to tear out the ceiling from below in an effort to fix the drain trap, when, in reality, it may be the overflow tube that needs tightening or a replacement gasket. The overflow drain is very likely the source of your leak if you routinely bathe with the water level quite high or if you have active children who slosh water playfully while they bathe.
Before You Begin
Locate the source of the leak. Start by checking the tile for grouting and caulking issues. These will only produce water leaks when the bathtub or shower is in use. These should be addressed before plumbing repairs can be assumed.
If it is a continuous leak appearing from the walls or flooring, it could be a pressurized water line leak. That means the water would be leaking even when the bathtub or shower is not in use. In that case, it's not a problem with the overflow tube.
If it is a leak on a drain line, it will show up only when the bathtub or shower is in use. Remove any access hatch or panel you have to expose the tub's plumbing connections. Run water in the tub and look for any water leaking directly below it. If you see water leaking, it is very likely you have loose connections in the drain fitting or the drain trap below the tub. Tighten or repair them as needed.
If running water in the tub causes no leaking, run the shower instead. If you think you see leaking from the faucet, look for signs of water splashing onto the tub spout, showerhead, or faucet escutcheon plate (valve plate). Cracked or missing caulk around these elements lets water behind the shower wall.
If the shower test does not reveal leaks, then the overflow tube is the most likely culprit.
Watch Now: How to Fix a Leaky Bathtub Overflow Tube
Equipment / Tools
- Utility knife
- Needle-nose pliers (if needed)
- Rubbing alcohol
- Replacement overflow gasket (as needed)
- Silicone caulk (as needed)
Check the Overflow Gasket
A tub overflow pipe seals against the tub with a ring-shaped gasket that typically lies between the flange around the pipe opening and the backside of the tub wall. The gasket is made of neoprene or rubber and can become brittle and cracked over time, leading to leaks.
To check the overflow gasket, remove the overflow plate. Do this by removing the screw or screws holding the plate in place and pulling off the plate. You may need to cut away caulking from around the overflow plate before it will come off. Cut the caulk with a utility knife.
Inspect the gasket. If it is heavily worn, cracked, or compressed, it's time to replace it. When in doubt, it's a good idea to replace the gasket to rule it out as a source of leaking. During the inspection, you may find that the overflow pipe assembly is loose or damaged. If so, it is an easy fix to replace the entire overflow assembly with new parts.
Remove the Old Overflow Gasket
Replace a worn or damaged gasket by first removing the old gasket. The overflow drain pipe usually has a little give, and you can push it backward (away from the tub) to gain some space to grab the gasket with your fingers or needle-nose pliers. Remove all of the old gasket, and clean around the tub hole and the drain pipe flange with a rag and rubbing alcohol to remove all grime and residue.
Install the New Gasket
Push the new gasket into the hole in the tub wall and carefully fit it against the flange around the opening in the drain pipe. Make sure it is fully seated against the flange so that it will make an even seal against the tub.
Overflow gaskets are often tapered to accommodate the angle of the tub wall; follow the manufacturer's instructions for how to work with the taper.
Reinstall the Overflow Plate
Fit the overflow plate back into position, making sure the opening (where the overflowing water flows out) is at the bottom. If the plate has a stopper assembly, carefully slip the stopper into the overflow pipe and slide the rod down until the plate meets the drain opening.
Secure the plate with its screw or screws. If there are two screws, tighten them a little bit at a time, alternating back and forth so that the gasket is compressed evenly against the tub.
Tub Overflow Troubleshooting Tips
If the overflow gasket is in good condition or if replacing the gasket does not seem to stop the leak, there are some other approaches you can try:
- Make sure the gasket is installed correctly and that it sits in the center of the tub overflow drain.
- Inspect the edge of the tub around the overflow plate for nicks or corrosion that can allow water to seep in behind it.
- Check to make sure that the overflow plate is screwed tightly into place and that the notch in the plate is facing down.
- Check the seal on other shower parts, remove chipping, old caulk, and apply new caulk as needed to ensure water can’t get behind the shower surround.