How Does A Bathtub Overflow Drain Work & Installation process
Posted by
Julian Gill
Updated on
September 27, 2023
Disclosure: Some of the links in this article may be affiliate links, which can provide compensation to me at no cost to you. You can read our affiliate disclosure in our privacy policy.

How Does A Bathtub Overflow Drain Work & Installation in 2023

There is nothing more refreshing like a nice bath in your bathtub after a long day at work. The tub is a fun and essential structure when it comes to taking a shower. However, it comes with some disappointments if not looked at properly.

Poor drainage can cause significant damage in your bathroom, something you’ll never want to happen. Therefore, you need a stable system that’ll pass your bathed-water effectively without causing any problem to the bathtub. An overflow drain is what you need to keep your tub clean and safe, as it deserves. This article will help you get a satisfying answer on the question, “How does a bathtub overflow drain work?” It’ll also highlight on Bathtub overflow drain installation.

How Does A Bathtub Overflow Drain Work

The model of an overflow

The bathtub drain is sectioned into two parts: the main drain and the overflow drain. The primary pipe is positioned at the bottom while the overflow drain is located some inches below the rim.

The two drains are both connected to tubes which are positioned below the bathtub, then emerged into one pipe. The overflow drain lacks a stopper unlike the main which has a plug or mechanical stopper.

How it works

Overflow saves you the clean-up effort and extensive damage in your bathing space. It is modelled to prevent an overflow before it takes place. Since it lacks the mechanism of stopping water from flowing, it continuously drains water that reaches its maximum level. It works well if the pipes are clog-free and if the water level stays a few inches below the rim of the bathtub. With the help of it, it prevents the water from splashing onto the floor.

The two types of overflow drain

The first type is a traditional overflow. With this kind of overflow, a hole is cut into the side of the bathtub, allowing collected water to drain. The second one is an integral overflow. It’s an unnoticeable opening created inside the tub to let out excess water.

Bathtub Overflow Drain Installation
Tools and materials : Screwdriver, Plumber’s putty or caulking, Channel locks
Attach the waste and overflow assembly

Install the assembly, making sure the top of the overflow tube aligns with the overflow opening on the bathtub. The drain arm should align with the drain opening in the bottom of the tub. Use channel lock pliers or solvent glue to permanently weld PVC connections.

Connect the drain fitting

Apply plumber’s putty around the drain opening, put the rubber washer on the drain end. Thread the drain fitting into the drain arm and tighten it using a drain wrench.

Attach the overflow cover dish

Place the gasket between the wall of the bathtub and the mouth on the overflow tube. The thicker side of the gasket should face down. Place the cover plate overflow opening and screw it tightly.

Test the installation

Wipe any excess putty around the drain fitting. Run water into the drain as you ensure there is no leakage in the tub.

How To Install A Tub Drain In A Concrete Floor
Concrete floor is heavyweight and a bit more expensive compared to other types of stories. Installing a tub drain may need special attention to fix it properly without damaging your place. Here is the simplest way to connect your pipe safely:
Select the right position of the drain

Select the right position of the drain where it’ll hold the tub and still be even on the concrete floor.

Insert a new threaded drain

Insert a new threaded drain down into the drain hole and over the male threads already sticking up. Ensure the drain is in line with the drain piping under and behind the tub.

Install an overflow assembly

Insert the rod, linkage, and plunger through the tube overflow hole and let it drop down until the overflow cover lines up with the overflow drain hole. Install the screws with a screwdriver and tighten down.

Thread in a spout tub pipe

Thread in a spout tub pipe through the tub spout hole and into the way connecting to the wall. Tighten using pliers.

Screw on the tub spout

Screw on the tub spout with the screwdriver. Finally, test if it’s flowing water smoothly.

Repairing Bathtub Overflow Drain Leakage
Overflow drain can leak anytime. Anything can destroy the drain, making it malfunction. When that happens, this is what you should do:
Find the leak

Find out the source of the leak, confirm the cause is overflow.

Check the overflow gasket

Check the overflow gasket and fix or replace the overflow pipe assembly if it’s loose or damaged.

Reinstall the overflow plate

Reinstall the overflow plate, making sure its opening is at the bottom. If the plate has a stopper, carefully slip the stopper into the overflow pipe and slide the rode down until the plate meets the drain opening.


How Do You Remove Bathtub Drain Stopper?

Hold the stopper’s base and loosen the knob sideways until it ‘s off. If the knob is too tight, wrap a rag and use pliers to loosen.

What Happens When A Bathtub Drain Stopper Gets Stuck In A Closed Position?

Apply two drops of a lubricant on the threads to loosen it, turn the knob using screws then pull the stem of the stopper.

What Happens When A Bathtub Drain Stopper Leaks?

Unscrew the stopper and fix it again tightly.

Bathtub Trip Lever Not Working, What’s Next?

Stop the flow of water and replace it.

How To Remove A Lift And Turn Stopper Without Screw?

Wrap a rag around it and use a hand to slide it off. If it’s too tight, apply a lubricant.

What Happens When A Bathtub Overflow?

Close the bathtub immediately and call a plumber to check your drain system.

Does Homeowners Insurance Cover Bathtub Overflow?

Some do. Confirm from your insurers if they cover for costs of your plumbing operations.

Does A Bathtub Have To Have Overflow Drainage?

Yes, for efficient let out of excess water.

How Long Does An Acrylic Bathtub Last?

The acrylic bathtub takes 10 to 15 years approximately.

Why Does My Tub Faucet Drip?

If you have a leaky tub faucet then it might be happen. If you not sure then check first the washer. Replace this with a new one if it gets worn out. If you would like to buy a new bathtub faucet then check out this – unbiased reviews of bathtub faucet.


Drainage is an important issue. For you and your family to enjoy a sweet and comfortable bath, you must ensure the drainage is well structured. A proper overflow drain will help you get rid of the unpleasant water that may block the drainage system and cause bad odor in your home. Ensure you install an overflow drain if you want a clean a bathroom, which you can confidently let your guest go to without feeling any shame. Use the information provided in the article and do what you have to do to make your bathroom a happy place!

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Julian Gill
Julian Gill is a mechanical engineer and working in the plumbing sector for the last seven years. To be a professional, Gill had completed the CPD (Certified in Plumbing Design) program successfully. Besides this, he also works in home improvement and remodeling.
Julian Gill
Hi! I’m Julian Gill.
My mission is to help people in purchasing decisions about home, kitchen and garden accessories.
Oh! And I’m also a plumber. I usually repair what husbands fixed.
Disclosure: Some of the links in this article may be affiliate links, which can provide compensation to me at no cost to you. You can read our affiliate disclosure in our privacy policy.

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