What Is an Overflow Drain? Types and Workings

If you are looking for a perfect solution to flooding problems associated with sinks and bathtubs then an overflow drain is what you need. These drain out excess water from sinks and tubs keeping your house free of flooding.

An overflow drain is an opening that helps prevent flooding in sinks and tubs by directing excess water to the drain pipe when it reaches a certain level. Traditional and integral overflow drains serve the same purpose but have different designs. Clogs and leaks affect overflow drains.

What Is an Overflow Drain? Types and Workings

What Is an Overflow Drain?

An overflow drain is a small opening fixed at a certain level of water basins that prevents flooding by rerouting any excess water to the drain pipe. However, the designs of overflow drains differ depending on sinks and bathtubs, but they all serve the same purpose.

Is An Overflow Drain Important?

Overflow drains come with many benefits that may include:

  • Prevent Flooding: Overflow pipes drain excess water beyond a specific set point hence there are no flooding problems.
  • Prevent Loss Associated with Flooding: Flooding may cause extreme damage to items within their surroundings. Overflow drains have made it possible to mitigate such problems.
  • Reduce Unnecessary Costs: Overflow pipes save you the money you would have spent on hiring experts to fix flooding problems. Also, other costs related to damages that flooding would have caused.
  • Enhance Drainage: Overflow drains create an air channel that prevents the buildup of intolerable yucky stuff.
  • Perfect Alternative for Drainage During Blockages: Sinks and bathtubs are often associated with clogs. In such instances, overflow pipes direct water into the main drainage. No flooding will occur, making you comfortably use your sink or bathtub.

As long as the overflow drain is properly installed and working correctly, your tub or sink won’t flood or develop other issues an overflow drain can solve.

Types Of Overflow Drains

The main types of overflow drains are the traditional and integral drains. However, there are others when it comes to other considerations such as the following:

1. Traditional overflow drain

Traditional Overflow Drain

Traditional overflow drains are holes cut into the tub to accommodate a drain installed on the inside or outside walls that collects excess water into the tub drain and later to the P-trap. 

There are various tub drains that guarantee compatibility with specific designs of bathtubs. It is essential to use the tub drain buying guide before making any step to secure one. 

2. Integral overflow drain

Integral Overflow Drain

Integral overflow drains come in similar designs as sink overflow drains. Openings are cut along the bathtub interior to drain extra water between the walls, sending it down to the tub drain. It is a perfect option for anyone who doesn’t like piping in their space since it is inbuilt into the inner tub wall.

Other types

3. Sink overflow drain

As the name suggests, sink overflow drains are openings fixed at certain levels of your sink that prevent overflowing if anyone accidentally leaves the faucet running or plumbing problems with the tap. Bathroom sink drains aren’t different from kitchen sink drains. They can be either traditional or integral in nature.

4. Tub overflow drain

Tub overflow drains are drainage located a few inches below the rim of your bathtub. They prevent excess water overflow that may be caused by leaving a running faucet, plumbing issues, and extra water levels when your body submerges in the bathtub. They’re also called shower overflow drains and can also be traditional or integral in nature.

5. Pop-Up Drain

A pop-up drain is a system designed to give you an option of sealing your gutter, making it hold water by simply pushing them to either close or open. There are two standard designs of pop-up drains that include:

A. With Overflow

This advanced pop-up has an overflow hole in the threaded nut which allows overflow water to flow down the pipe. They are mainly composed of brass with an antique rubbed bronze finish making them last for long.

B. Without Overflow

Without overflow designs are ideal for baths and vessels without overflow. The design enhances drainage and is easy to install. 

6. Floor Drains

Also known as floor traps, floor drains are overflow drains mainly located on the floor of your laundry rooms, bathrooms, kitchens, and sinks. These drains come in various designs all meant to help drain any water spilled on the floor thus reducing the chances of flooding. 

They only work in instances when there are overflow problems. Pre-planning and simple maintenance are the main ways to enhance their efficiency.            

How Does an Overflow Drain Work?

Overflow drains work in the following steps:

  1. Water flows through the main drain into the drain pipe.
  2. If the main drain is clogged or plugged, the water will begin rising.
  3. As the water level reaches the level of the overflow drain, it flows out and into the drain pipe.
  4. If the water from the faucet is equal to or less than the amount drained by the overflow drain, the sink or tub will not flood.
  5. Overflow drains also have P-traps which help keep out unwanted gases from the sewer.

The main parts of an overflow drain are the cover, cover screws, overflow trap, stopper, drain elbow, overflow washer, overflow pipe, waste arm, and rubber gasket.

They drain excess water that may pass above the set limit into the drainage system. They are ideal in case of faulty faucets and any overflowing causing problems. Extra water is drawn out, preventing spillage and flooding.

Overflow Drain Problems

Here are common problems you are most likely to face with your overflow drains, their prevention, and appropriate solution: 

1. Leaking

Leaking is a condition when overflow pipes drain water into unintended areas in your living areas, posing significant damages and risks. Any signs of leaking necessitate immediate attention for fixing. 


  • Faulty valves in the water tanks
  • Worn out pipes that will cause leakages
  • Improper installations
  • Loose connections


  • Fixing faulty valves or replacing them with new ones.
  • Using high-quality overflow pipes that are more durable.
  • Choosing a reliable expert for your overflow drain installation.
  • Fixing loose connections.

2. Clogging

Although clogging may arise, it is rare with sinks, and bathtub overflow drains. It necessitates an immediate repair action of fixing the drainage systems, and the overflow drains when it occurs.


  • Hair intake into the overflow drains
  • Continuous use of overflow drains
  • Foreign particles enter the overflow drains.


  • Fixing faulty drainage systems.
  • Minimizing exposure of hair to your bathtub
  • Preventing unwanted materials to your sinks and bathtubs.

You can easily clean a clogged overflow drain with vinegar the same way you clean a smelly shower drain.

3. Slime Build Ups

When slime builds up in your overflow drains, some blockages alter their efficiency, necessitating immediate attention. Slime buildups are inevitable regardless of the design of the overflow drain and its installation.


  • Regular passage of soaps, gels, lotions, toothpaste, and creams in the overflow drains.
  • Irregular overflow drains checks.


  • Regular overflow drains service

Slime and calcium buildup is cleaned using a mix of baking soda and white vinegar.

Do Tubs and Sinks Need Overflow Drains?

Your tubs and sinks need overflow drains to enhance their performance. Installing overflow drains to your tubs and sinks guarantees you a safe, dry place free from floods. In addition, they are a great solution to mitigate risks associated with overflow problems.

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