A bathtub overflow drain is designed to channel excess water from the tub into the drain line and effectively prevent the tub from overflowing and flooding the bathroom.
This fail-safe fixture can however be a problem on its own. Water may eventually start to leak from the overflow drain and damage your flooring or the ceiling of the floor below.
But why is the bathtub overflow drain leaking? And what can you do to stop it?
A leaking bathtub overflow drain is caused by a cracked, worn out or misaligned gasket/seal. To stop the leak, remove the tub overflow drain cover plate and replace the gasket then install the plate back.
Another thing you can do albeit a temporary one is use a bathtub drain overflow cover. The cover completely seals off the overflow drain so there is the risk of your bathtub overflowing.
If a bathtub is leaking through the ceiling, it could be the tub’s main drain or the overflow drain. To find out which drain is leaking, you will need to test both drains independently but you may need to remove a section of the ceiling or use an access hatch/panel.
Troubleshooting the Problem
It is not always easy to find the source of a leak when you have issues with your bathtub drain. This is especially trickier if you have a shower-tub combo.
As a matter of fact, some leaks are so slow and therefore not that easy to notice. You will only notice stains in the basement ceiling or damp/moldy walls.
There is however a few steps you can take to determine the source of the leak. Does the leak happen when taking a shower or when soaking in the tub?
That is the first question you should ask yourself. Or is it a continuous leak?
The first thing you will need to do is inspect the shower tiles closely. Check if the caulk or grout used between the tiles has come off. If indeed it has, that creates gaps for water to leak through especially when showering.
You will therefore need to fix that problem. You can easily fill the gaps with caulk or grout without calling in a plumber.
If the shower tiles caulk or grout is intact, the problem is with one of the drains. Both the tub’s main drain and overflow drain have the potential to leak.
To find out with drain is leaking, look for an access hatch or panel so that you can have a close look of the the tub’s plumbing. If you don’t already know it, the main drain and the overflow drain use the same drain line and are connected together using a tee.
After locating the bathtub’s drain, turn on the faucet and let the water drain out through the main tub drain. If you see a leak the problem is with the main drain and not the overflow drain.
That is in most cases caused by a loose connection in the drain line or P-trap, which you again can fix easily using a wrench.
If there is no leak then the problem is with overflow drain. You can go ahead and test it by forcing some water through the bathtub’s overflow opening.
Note: If you see a continuous leak from the ceiling of the floor below the bathtub even when nobody is using the bathtub or shower, you could be dealing with a leaking water supply house.
Bathtubs are supplied with pressurized water using 2 pipes, one carrying hot water and the other one carrying cold water. In that case you may want to turn off water supply to the bathtub or whole house until you have fixed the problem.
Apart from the bathtub or shower drain, leaks through a ceiling can also be caused by leaking bathroom sink or toilet drains.
With a leaking toilet drain, water may pool around the base of the toilet or leak through the flooring to the ceiling of the floor below. This problem is usually caused by a bad wax ring. Replacing the wax ring will surely fix the problem.
How to Fix It
If you are sure that the source of the leak is the bathtub overflow drain, half of the problem has been solved already. As I had mentioned, a leaking bathtub overflow drain is caused by a bad gasket.
The gasket is normally made of rubber or neoprene. Its function is to create a watertight seal between the overflow drainpipe and the bathtub.
The overflow drain pipe has a flange which allows it to be connected to the bathtub. As with other such connections, you would need a gasket which you can compress and create a good seal.
After years of usage, the gasket wears out or it cracks (water quality can affect it) resulting in leaks. It is also good to remember that a loose or damaged overflow pipe can result in leaks.
This is how to fix a leaking bathtub overflow drain by replacing the gasket:
1. Remove the cover plate
The bathtub overflow cover plate is usually connected to the tub using 2 long screws. This plate is mainly for cosmetic purposes.
Use a screwdriver to loosen the screws attaching the plate. It would be a good idea to first plug off the tub drain to prevent dropping the screws inside the drain line.
Note: If your bathtub has a trip-lever drain stopper, the lever is mounted on the cover plate while the stopper assembly runs through the inside of the overflow drain.
In this case, you will need to pull out the stopper assembly slowly out of the drainpipe. I like to first pull it upwards and then outwards.
2. Remove the Old Gasket
With the cover plate and the trip-lever stopper out of the way, you can now see the old gasket. The only way to find out if it is the cause of the leak is by removing it and inspecting it.
The good thing is that the overflow drainpipe is flexible and you can therefore push it back a little. This allows you to use needle-nose pliers to grab the gasket and pull it out.
If you don’t have needle-nose pliers, you can use a piece of wire or any other thing which can help you pull out the seal.
If the gasket is badly deteriorated, you will notice that there will be several pieces of it left stuck inside. Make sure that you remove all the pieces.
3. Install the New Gasket
Now that you have removed the old and problematic gasket, start by cleaning the area around the tub hole and overflow pipe flange using a rag. That will help the new gasket seal better.
While installing a bathtub overflow drain gasket, you need to be careful with how you put it in. If you inspect the gasket keenly, you will notice that it is tapered/beveled.
The taper is designed to take care of the angle of the tub’s wall. You will therefore need to make sure that the thin side is at the top and the thick side at the bottom.
Start by lubricating the gasket by applying silicone grease all around it. This will make for an easy installation.
The next thing is to carefully push the gasket through the bathtub overflow drain opening and fitting it around the overflow pipe flange. As I mentioned, the overflow pipe has a little play to help you position the gasket properly.
4. Install the Cover Plate and Stopper
With the new gasket in place, the only thing remaining is to install the cover plate. If you have a trip-lever stopper, you need to push the whole assembly drain while making sure that the 2 connecting rods do not get entangled.
If they get entangled, the stopper’s plunger cannot get to the bottom of the overflow drain and as a result will be unable to plug the drain when you want to fill the tub.
Method 2: Use an Overflow Drain Cover
This is not a common method, but you can decide to use it and as matter of fact people have actually used it for a long time now.
Bathtub overflow drain covers are used to seal around the overflow drain opening. The reason people do it is to have more water in the tub.
As you already know, the overflow drain denies you a few inches of water depth in the tub. Although the overflow drain is important in preventing the tub from overflowing, you can see it has its limitations too.
You can therefore decide to do away with the overflow drain and instead plug it off. That also means you will need to actively monitor your tub as it fills to preventing flooding your bathroom.
There are temporary and permanent bathtub overflow covers. You can therefore determine which will work best for your needs.
If your bathtub has a trip-level, bathtub, a temporary one will be ideal. You can plug the drain before filling the tub and often bathing remove the cover and drain the tub. The temporary covers can be used again though.
And basically that is how to fix a leaking bathtub overflow drain. I hope this post was helpful.