Why Do Bathtubs Have An Overflow Drain?

Overflow drains serve a vital purpose in any bathtub: to prevent overflows and potential damage to your home.

They are strategically positioned a few inches below the rim of the bathtub, ensuring that excess water has a controlled escape route rather than spilling over to the floor.

This feature not only safeguards your bathroom but also provides peace of mind as you enjoy your bath.

What is a Bathtub Overflow Drain

A bathtub overflow drain is a plumbing feature that you can find in most bathtubs. It is a small hole located near the top of the tub, typically either below or right at the level of the spout.

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The primary purpose of this drain is to prevent water from spilling over the edge of the tub and onto the floor, causing potential water damage to your bathroom.

Purpose of Overflow Drains

Overflow drains serve various roles in ensuring the proper functioning of your bathtub. Here are some key reasons for their existence:

  • Preventing water damage: The main purpose of an overflow drain is to help protect your bathroom from water damage. If water continues to flow into the tub while it’s already full, it can quickly lead to water spilling over the edge, which can damage your flooring and other parts of the bathroom.
  • Regulating water level: The overflow drain helps you maintain a particular water level in the bathtub. If you accidentally leave the faucet running or if the tub fills up too quickly, the drain serves as a safety mechanism, letting excess water escape through the hole rather than overflowing the tub.
  • Swirl effect: Another benefit of having an overflow drain is that it encourages water to circulate in the tub, creating a swirl effect. This swirling motion helps keep the water temperature even throughout the bath, making for a more comfortable and relaxing experience.

Parts of Overflow Drain

Overflow Cover

The overflow cover is an essential part of your bathtub’s drain system. It is a disc or plate that is connected to a pipe behind your tub’s wall.

This cover prevents water from overflowing and causing damage to your bathroom floor and the surrounding area. It is typically located just below the faucet, so you’ll easily notice it when you’re filling your tub.


A gasket is a vital component in the overflow drain system. It is a rubber or foam seal located between the overflow cover and the bathtub. The gasket’s primary purpose is to create an airtight seal that prevents water from leaking out of the overflow drain and causing potential damage to your plumbing system.

Drain Trap

The drain trap is another essential part of your bathtub’s overflow drain system. It is a curved pipe located beneath the bathtub, connecting the drain to the plumbing system.

The drain trap catches hair, debris, and other particles that may obstruct the flow of water in your pipes. It also serves as a barrier to prevent sewer gases from entering your home through the drain.

Importance of Overflow Drains

Preventing Flood Damage

Overflow drains are essential for protecting your home from potential flood damage. These drains ensure that excess water in your bathtub is channeled away before it can spill over the edges, preventing costly damage to your bathroom floors and walls.

Handling Excess Water

Another important function of overflow drains is managing excess water. It’s not uncommon for you to accidentally overfill your bathtub or experience a sudden surge of water when using a showerhead.

Under these circumstances, the overflow drain serves to regulate the water level, preventing it from accumulating and causing issues like water damage, mold growth, and even structural damage.

Overflow Drains in Different Fixtures

Bathtub Overflow Drains

When it comes to bathtubs, an overflow drain serves a crucial purpose. It helps prevent water from spilling onto the bathroom floor and causing damage.

You might have noticed the small hole near the top of your bathtub, just below the faucet. This is the overflow drain.

The overflow drain connects to the main drain of the bathtub, which leads the water back to your home’s plumbing system. When the water reaches a certain level, it starts to flow into the overflow drain, ensuring it doesn’t reach the edge of the bathtub.

Sink Overflow Drains

Similar to bathtubs, sinks also have overflow drains, although their design and appearance might vary. In most sinks, you will find a small hole near the top edge or close to the faucet.

The purpose of this hole is to prevent water from spilling onto the counter or floor in case the main drain becomes blocked or the tap is left running unattended.

Sink overflow drains work similarly to those in bathtubs. Water flows into the overflow channel, then reaches the main drain and exits the sink without making a mess on your countertop or floor.

Additionally, sink overflow drains can help reduce the risk of accidental flooding and potential damage to your bathroom or kitchen.

Common Problems with Overflow Drains


Clogs can occur in the overflow drain of your bathtub due to the buildup of hair, soap scum, and other debris.

Here are a few ways to address this issue:

  • Regularly clean your overflow drain to prevent the accumulation of debris.
  • Use a drain cover to catch hair and other particles before they reach the drain.
  • Inspect and clean the drain pipe for potential clogs.


Leaks in the overflow drain system can cause water damage and mold growth.

To prevent these issues, pay attention to the following points:

  • Check for water stains or signs of dampness around the overflow drain and the surrounding area.
  • Inspect the gasket or seal between the overflow plate and the tub for wear or damage.
  • Ensure the connections between the drain pipe, overflow pipe, and waste pipe are properly tightened.

Materials Used for Overflow Drains

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Metal is a common material used for overflow drains due to its durability and strength. You might often see brass, stainless steel, or chrome-plated materials in bathtubs.

Metal overflow drains tend to resist corrosion, ensuring your bathtub’s functionality for a long time.


Plastic overflow drains offer a cost-effective alternative to metal ones. They are lightweight and easy to install. PVC (polyvinyl chloride) and ABS (acrylonitrile-butadiene-styrene) are two popular types of plastic used in these drains.

While plastic overflow drains may not be as durable as their metal counterparts, they still provide sufficient strength for everyday use.

Furthermore, plastic drain components are non-corrosive and generally require less maintenance.


In some cases, rubber components can be found in overflow drains. They play a crucial role by acting as gaskets or seals between the drain assembly and the bathtub itself. This helps prevent leaks and maintains a watertight seal.

Rubber is often used in these applications because it is flexible and provides a reliable seal between the various components of the overflow drain system. Keep in mind that the primary material used for the overflow drain itself is still usually metal or plastic.

Types of Overflow Drain Covers

When choosing an overflow drain cover for your bathtub, it’s essential to understand the different types available, so you can make the best decision for your needs.

This section will briefly discuss traditional overflow drains, integral overflow drains, and their respective covers, including overflow cover plates.

Traditional Overflow Drains are the most common type you’ll encounter in bathtubs. They consist of a circular opening located near the top of the tub.

To prevent water from overflowing, a cover is placed over the opening, allowing water to escape through a separate drain. There are various covers for traditional overflows, such as:

  • Metal Covers: These are durable and long-lasting and come in a range of finishes to match your bathroom fixtures.
  • Plastic Covers: A more budget-friendly option, these covers are lightweight and easy to install. However, they may not be as durable as metal options.

Integral Overflow Drains are built directly into the tub, making them less visible than traditional options. They usually have a narrow channel running along the inside edge of the bathtub, which allows excess water to flow back into the drain.

Covers for integral overflows include:

  • Overflow Cover Plates: These thin plates are installed over the opening of the integral channel to prevent debris from entering the drain. Overflow cover plates are typically made of metal, like brass or stainless steel, providing durability and a sleek appearance.

Maintenance of Overflow Drains

Plunger Bathtub

Preventing Clogs

To prevent clogs in your overflow drain, make sure to clean and inspect it regularly. Remove any debris, such as hair or soap scum, from the drain stopper. You can use a brush or cloth to clean the openings of the overflow drain.

Also, consider using a drain cover in your bathtub to catch any debris before it enters the drain pipe.

Occasionally, use a snake or similar tool to clear out any buildup in the drain line. This will help maintain proper water flow and reduce the risk of a clogged drain. Be careful not to damage the pipe or other plumbing components when using a snake.

Keep in mind that some overflow drains are connected to the main drain line. In these cases, addressing the main drain clog is crucial to prevent overflow drain issues.

Addressing Leaks

Leaky overflow drains can cause water damage to your bathroom and lead to costly plumbing repairs. To address leaks, first, inspect the drain pipe and connections for any visible damage or loose parts.

If you notice any issues, tighten the connections and replace any damaged components as necessary.

Next, check the gasket between the bathtub and the overflow drain cover. If the gasket is worn out or damaged, water can seep through it and cause leaks. Replace the gasket to ensure a watertight seal.

In some cases, the leak may be due to a problem with the drain line itself. If you suspect that your drain line is causing the issue, contact a professional plumber for assistance.

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