What Is A Bathtub Drain Kit?

In this blog post, you’ll read:The bathtub is a common thing for luxury. And if you have a bathtub, then a drain kit for the tub is compulsory. But most of us don’t know about its functions. This article covers bathtub drain kit functions, features, installation process, etc...

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A bathtub drain kit is a collection of components required to ensure effective drainage and prevent water leakage from a bathtub. It typically facilitates water flow from the tub into the plumbing system and provides a mechanism to retain water when necessary. Whether installing a new bathtub or replacing a worn-out drainage system, understanding what a bathtub drain kit entails is crucial.

Components of a Bathtub Drain Kit:

  • Drain and Overflow Assembly:
    • Tub Drain: This is the primary hole where water exits the tub. It typically comes with a strainer to catch hair and other debris, preventing them from entering the drainage pipes.
    • Overflow: This safety feature prevents water from spilling out of the tub if it gets too full. It’s typically positioned a few inches below the top of the bathtub and directs excess water back into the drain.
  • Stopper or Closure:
    • This component allows you to fill the tub by blocking the water flow out of the drain. Various types exist, including toe-touch, push-pull, flip-it, lift-and-turn, and the classic rubber stopper.
  • Drain Elbow:
    • This bent pipe connects the main drain and the overflow channel, ensuring water flows smoothly into the central drainage system.
  • Waste and Overflow Plate:
    • Often situated above the overflow opening, this plate may have a lever or switch. In some configurations, it can be used to control the stopper.
  • Gaskets or Washers:
    • These are essential to ensure a watertight seal at various junctions, preventing leaks.
  • Drain Shoe:
    • This component lies beneath the tub and connects the drain to the horizontal waste pipe. It acts as a kind of “junction box” for the drain.
  • Linkage Assembly (for some kits):
    • Found in some older or more traditional setups, this series of rods and balls helps control the drain stopper’s movement from the overflow plate.
  • Connecting Pipes:
    • These pipes ensure a seamless water flow from the tub to the home’s plumbing system.

When shopping for a bathtub drain kit, it’s essential to ensure compatibility with your tub and existing plumbing. For instance, deeper tubs may require an extended overflow and waste, while the diameter of the pipes needs to match your home’s plumbing standards. Materials matter, too: while plastic kits might be more affordable, metal (like brass) is generally more durable and corrosion-resistant. Always consult a professional plumber or expert if unsure about the right fit for your bathroom.

Bathtub-Waste drain kit
Bathtub-Waste drain kit

Bathtub Drain Kit Size?

Regarding the sizes of bathtub drain kits, several dimensions come into play. These dimensions cater to varying bathtub designs, plumbing configurations, and homeowner preferences. Here’s a breakdown of the sizes you should be aware of when considering a bathtub drain kit:

  • Drain Diameter:
    • The most common drain diameters are 1 ½ inches and 1 ⅜ inches. The size refers to the inner diameter of the drainpipe.
  • Overflow Height:
    • The distance from the base of the tub to the center of the overflow hole varies depending on the depth of the bathtub. Standard bathtubs commonly have an overflow height of around 14 inches to 16 inches. However, deeper soaking tubs might have overflow heights of up to 20 inches or more.
  • Drain Shoe Length:
    • The drain shoe is the piece that connects the tub drain to the overflow. The length can vary, but common sizes range from 12 inches to 15 inches. However, choosing the length is essential based on the tub’s depth and the specific installation requirements.
  • Waste and Overflow Pipe Diameter:
    • The diameter of the waste and overflow pipe is usually consistent with the drain diameter, often at 1 ½ inches or 1 ⅜ inches.
  • Linkage Assembly Length:
    • If your drain kit uses a linkage assembly to control the stopper, the length of this linkage can vary. Selecting a length that corresponds with the overflow height and the specific mechanics of your tub’s drain is crucial.
  • Drain Flange Diameter:
    • The drain flange, which covers the drain hole’s opening, typically has a diameter ranging from 2 ⅞ inches to 3 ¼ inches, though this can vary based on the design and brand.

When selecting a bathtub drain kit, always check the specifications and measurements of your bathtub and existing plumbing setup. It might be beneficial to consult with a professional plumber or take measures of the existing drain (if you’re replacing it) to ensure compatibility.

Remember that while standard sizes exist, there can always be exceptions, especially with custom-designed or imported bathtubs. Always measure twice to ensure accuracy and reduce the chances of purchasing incompatible components.

bathtub drain waste and overflow
bathtub drain waste and overflow

Functions of Bathtub drain 

All a bathtub drain kit connects the tub and water flow pipe… and passes water from the tub to the drain. Also, it helps to keep the water in the tub. Let’s see how.

You know there are two different assemblies, ‘plunger’ and ‘pop-up.’ Both work with a lever, but their working principle is slightly different. 

When you press the lever down in a plunger assembly, it lifts the rod. The rod pulls the plunger up, and the drain opens for water flow. Similarly, if you press the lever up, the plunger will go down and seal the drain. As a result, water cannot flow through the pipe.

The pop-up assembly is similar, but the change is in the main drain section. You can control it by the lever or the stopper. When the lever goes down, it lifts the rod along with the spring. After that, the spring pulls the stopper down with the help of the rocker’s arm. Therefore, the water flow path is sealed, no water flow happens, and vice-versa. Also, you can push the stopper with your feet to control it.

And the overflow is the same for both assemblies. If the user leaves the faucet open or fills the tub above a certain level, the overflow removes or drains the excess water.

The raw materials used for bathtub drain kits vary depending on the product’s design specifications, durability needs, and cost factors. Here are some common raw materials:

bathtub drainer cable waste sink valve pop up drains
Bathtub drainer cable waste sink valve pop-up drains

Raw Materials


  • Stainless Steel: Widely used due to its corrosion resistance and strength. It’s often used in the construction of the drain flange and sometimes for the drainpipe.
  • Brass: A robust and durable material often used for high-end or commercial-grade bathtub drain kits. It’s also corrosion-resistant and can be easily molded into various shapes.
  • Zinc Alloy: Usually used for the drain stopper or linkage mechanism. It’s less expensive than stainless steel or brass but may not offer the same durability or corrosion resistance level.
  • Aluminum: Not as common as stainless steel or brass but still used for its lightweight and corrosion-resistant properties.


  • PVC (Polyvinyl Chloride): Frequently used for overflow and waste pipes, as it’s resistant to corrosion and relatively easy to install.
  • ABS (Acrylonitrile Butadiene Styrene): Similar to PVC but generally considered stronger and more resistant to impact. It’s also used for overflow and waste pipes.
bathtub cable strainer drain with filter bathtub cable controller drain waste bath waste and
Bathtub cable strainer drain with filter bathtub cable controller drain waste bath waste and

Other Materials:

  • Rubber Gaskets: These are essential for ensuring a watertight seal at various connection points in the drain assembly.
  • Silicone Sealant: Often used to secure gaskets and create waterproof seals.
  • Fasteners: Screws and bolts made of corrosion-resistant materials like stainless steel or sometimes brass.
  • Finishes: These are not raw materials per se but are applied to the visible parts of the drain for aesthetic reasons. Common finishes include chrome, nickel, bronze, and even gold plating for high-end models.


  1. Linkage Assembly: Often made of a combination of metal and plastic components. The materials chosen will depend on the specific design and load-bearing requirements.

When selecting a bathtub drain kit, consider the durability and longevity of these materials, especially if the drain will see heavy use or if you have hard water, which can be corrosive over time. Always check with the manufacturer or a professional to ensure you choose the best materials for your specific needs.

Bathtub drain kits are vital in our residential and sometimes commercial spaces. These kits, which include the necessary components to connect the bathtub to the household plumbing system, ensure smooth water drainage from the tub. Let’s delve into the applications and where these kits are commonly used:

Residential Applications:

  • Standard Bathtubs: This is the most common application. Almost every home with a bathtub will have a drain kit installed to ensure efficient water flow out of the tub and into the household drainage system.
  • Whirlpool and Spa Tubs: These luxury bathtubs have unique requirements due to the jets and extra water volume. The fitting drain kit ensures they empty efficiently without straining the plumbing.
  • Freestanding Bathtubs: These types of tubs are becoming increasingly popular in modern homes. They require specialized drain kits that can accommodate their standalone design.
  • Shower Combos: Many homes have bathtubs that double as showers. The drain kits in these combos need to handle the rapid flow of water, especially during showers.
trip lever bathtub drain and parts
trip lever bathtub drain and parts

Commercial Applications:

  • Hotels and Motels: Guest rooms equipped with bathtubs will need drain kits. Considering the frequency of use in such settings, the drain kits might be more robust and durable.
  • Gyms and Health Clubs: Some upscale gyms and clubs offer bathtub facilities, especially in spa sections. Drain kits here ensure efficient water flow even with high usage.
  • Hospitals and Rehabilitation Centers: Therapeutic bathtubs in these places help patients recover or relax. Efficient and hygienic drainage is essential, making drain kits vital.

Specialized Applications:

  • Pet Bathing Stations: Some modern homes or pet grooming facilities have specialized tubs for pet baths. The fur and other debris require the drain kits to have efficient straining capabilities.
  • Accessible Bathtubs: There are specially designed bathtubs for older people or individuals with mobility issues. Drain kits for these tubs often come with easy-to-operate mechanisms.

Outdoor Applications:

  • Outdoor Jacuzzis and Bathtubs: These are found in resorts, luxury homes, or relaxation retreats. The drain kits here have to withstand external environmental factors.

How To Install A Bathtub Drain Kit

The installation process of a bathtub drain is pretty simple. The whole process is similar for both types of assemblies. So, we will instruct you on the pop-up type drain installation. If you follow this one properly, you can do it for both types.

Required Tools

Make sure to have these tools before starting installation:

  • Wrench
  • 2. Silicone Gel
  • 3. Hack Saw Blade
  • 4. Strainer Setting tool
  • 5. Teflon Tape

Installation Process

Follow these steps sequentially to install a bathtub drain kit in your tub:

  • Step 1: Disassemble

Most of the time, you’ll receive drain kits disassembled. But if you get it assembled, you need to open up the parts to install it. Remove the assembly’s stopper, overflow pipe, main drain pipe, and Tee pipe. Also, an open rod joins from the overflow pipe, and the rocker’s arm joins from the main drain pipe.

  • Step 2: Install Overflow and Main Drain Head

Take the back of the overflow section’s head and smear some silicone. Then, put the black rubber gasket on it and put some silicone on the gasket. After that, hold it close to the bathtub hole from the outside. Then, place the front part of the overflow sections’ head from inside to attach them. Now, make it hand-tight with the strainer setting tool.

Similarly, install the main drain head without a stopper at the bottom hole of the tub.

  • Step 3: Measure and Cut the Pipe

You may have two long pipes, one for overflow and the other for the main drain. But you cannot connect them properly with your tub because each tub has different measurements. 

To take measurements:

  1. Put one pipe inside the overflow parts’ head behind the tub and another in the main drain head.
  2. Place the Tee pipe with them (just as the whole system assembles) and mark where both tubes meet the Tee entrance.
  3. Cut the extra pipe with the hack saw blade.
  • Step 4: Merge Them Into One

You can see a compression nut and a ferrule on two ends of the Tee pipe; the other has only a pipe. Undo the nuts and ferrules from the Tee. After that, place the overflow pipe perfectly with the overflow head part. Now insert one nut followed by the ferrule on the overflow pipe. Then connect the rod and spring mechanism from the upper side of the Tee and screw up the nut to join the Tee and overflow.

Similarly, insert the main drain pipe and connect it with the middle leg of the Tee pipe. The whole assembly is merged into one now.

  • Step 5: Screw Up

Undo the bottom pipe from the Tee and bend some Teflon tape at its screw part to secure the leakage. Then, place it where it was. Now take the wrench and screw up all the nuts and joints of the Tee pipe.

Step 6: Install the Stopper and Test it.

Everything is good to go, but the stopper is left. Place the stopper at the main drain entrance and screw that up to fit. Now, you can test the total system, including the stopper. I hopeverything’s’s running well.

That’s how you can install the pop-up drain kits. You can install the plunger types following these steps. There is just one change in plunger-type installationPlace the plunger inside the Tee at the end of the main drain pipe.

trip lever bathtub overflow inside structure
Trip lever bathtub overflow inside a structure


In conclusion, bathtub drain kits are not a complex thing. Now that you know its functions, you can easily determine if there’s any problem. Also, you’ll be able to decide whether you can fix that problem or need to call a plumber.

One last thing: if you’re looking for high-quality and good-looking brass bathtub drain kits, Please check Hofen Drain Kits. You can order online or direct contact us to place an order from anywhere. 

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