Complete Guide To Basin Waste Trap

In this blog post, you’ll read:A basin waste trap is the most common part used in a basin. You will find it connected with the waste pipework of a Basin. It prevents foul-smelling gas and bacteria from coming into your home. This trap only works when there is water in that trap, which makes a water seal. The size of the basin waste trap depends on the waste pipework size. Here, we discuss some common basin waste traps to understand which needs you.

Table of Contents

What is a Basin Waste Trap

A basin waste trap is the most common part used in a basin. You will find it connected with the waste pipework of a Basin. It prevents foul-smelling gas and bacteria from coming into your home. This trap only works when water is in that trap, which makes a water seal. The size of the basin waste trap depends on the waste pipework size. Here, we discuss some common basin waste traps to understand which needs you.

Complete Guide to Basin Waste Trap


Every modern home, while varied in design and function, shares a common need: efficient waste management. The basin waste trap, a humble yet crucial plumbing component, ensures that our living spaces remain clean and free from the undesirable odors of the sewer system. But what is a basin waste trap, and why is it so essential? Let’s delve deeper.

The Functionality of a Basin Waste Trap

Understanding the Basics:

At the core of the waste trap’s function is the water seal. This feature allows water from the tap to flow through while blocking sewer gases from escaping the pipe. Understanding the basics of this dual function can guide your buying decisions and help you troubleshoot issues.

Mechanism and Purpose:

  • Water Seal: By design, the trap retains a specific amount of water that acts as a seal. This water barrier ensures that harmful and foul-smelling sewer gases don’t infiltrate your home. Picture it as a water-based shield, constantly guarding against these undesirable elements.
  • Debris Collection: Over time, sink usage leads to an accumulation of particles and debris. Without a trap, these could travel down the pipes, leading to clogs in more significant, often harder-to-reach parts of your plumbing system. The trap plays the role of a catchment area, collecting these particles before they become problematic.

The sheer importance of this simple device becomes more evident when one considers the potential health hazards and inconveniences that could arise in its absence.

Types of Basin Waste Traps

Diving Into Varieties:

While they all serve a similar core function, several trap designs cater to various needs and basin setups.

Common Types:

  • Bottle Trap: This design, reminiscent of a bottle, is frequently chosen for basins where the plumbing is in plain view. With a sleek, often chrome or metallic finish, they’re as much a design choice as they are functional.
  • P-Trap: The ubiquitous P-trap, aptly named for its P-like shape, is the workhorse of the waste trap world. Found in countless homes, it’s a testament to its efficiency and reliable design.
  • S-Trap: Not to be left out, the S-trap, while similar in function to the P-trap, boasts a design better suited for basins with a floor-based waste outlet.

Understanding these variations is pivotal in ensuring your basin setup is optimized for efficiency and aesthetic appeal.

Material Matters: Choosing the Right One for Your Basin

Weighing the Options:

The trap’s material can directly influence its longevity, functionality, and overall fit with your bathroom or kitchen’s design.

Material Insights:

  • Plastic: Beyond its lightweight nature and resistance to corrosion, plastic traps, often made of PVC or ABS, tend to be more pocket-friendly. They’re robust and can easily fit into various bathroom designs without standing out.
  • Brass: Oozing an aura of classic sophistication, brass traps, especially those adorned with chrome plating, add a touch of luxury. Beyond aesthetics, they’re notably resistant to rust.
  • Stainless Steel: Embodying strength and modern design, stainless steel traps are chosen for those seeking durability paired with a sleek, contemporary look.

Each material has unique benefits, and the choice often boils down to personal preference, budget, and design considerations.

Standard sizes

Basin waste traps come in a variety of sizes and configurations, catering to different types of sinks and plumbing requirements. The size you’ll need often depends on your basin type, its application, and regional plumbing codes or standards. Here are some common sizes and considerations regarding basin waste traps:

  • Diameter of the Trap Outlet:
    • Standard Sizes: The outlet, which connects the trap to the waste pipe in the wall or floor, typically comes in two main sizes: 1 1/4 inches (32mm) and 1 1/2 inches (40mm). The former is usually suitable for bathroom basins, while the latter is more common for kitchen sinks.
  • Diameter of the Trap Inlet:
    • Standard Sizes: The inlet, which connects the trap to the basin waste, generally has a size of 1 1/4 inches (32mm) for most bathroom basins.
  • Depth and Configuration:
    • Depending on the space available under the basin and the type of basin (wall-mounted, pedestal, vanity unit), you might choose between shallow or deep seal traps. The ‘seal’ refers to the amount of water retained in the trap to prevent sewer gases from coming up. Common depths include 50mm, 75mm, and 100mm.
    • Traps can also have configurations like P-trap (where the waste outlet exits through a wall) or S-trap (where it exits through the floor).
  • Space-saving designs:
    • For bathrooms or kitchens where space is at a premium, space-saving trap designs have a more compact profile, allowing for more storage space or simply a less cluttered look.
  • Telescopic or Adjustable Traps:
    • Some traps come with an adjustable section, which allows the height or length of the trap to be altered to fit the available space and alignment better.
  • Extensions and Converters:
    • If you are replacing or upgrading an existing trap, there might be a slight size difference between the old and new systems. In such cases, trap extension pieces or size converters can be handy.

When choosing the right size for a basin waste trap, measure the existing plumbing (if you are replacing a trap), consider the type of basin you have, and ensure that the trap you purchase meets local building codes or standards. If in doubt, consulting with a plumber or specialist can clarify the right size and type of trap for your basin.

Installation: Step-by-Step Guide

Getting It Right:

A proper installation is the bedrock of a functional waste trap, ensuring that you won’t face unforeseen leaks or inefficiencies.

Installation Breakdown:

  • Preparation: Before diving in, ensure you have all the necessary materials. This includes the trap kit, a wrench, and a plumber’s tape. Lay them out so you have everything within arm’s reach.
  • Removal of The Old Trap: If you’re replacing an existing trap, approach its removal carefully. Gently disconnect, ensuring not to exert undue force that could damage adjacent pipes.
  • Sealing & Securing: As you fit the new trap, use the plumber’s tape on threaded connections. This ensures a watertight seal, preventing any future leaks. Once aligned with the waste outlet and pipe, tighten securely, but be wary of over-tightening, which could damage the threads.
  • Test Run: With the trap installed, run water to ensure no leakage, and that water flows smoothly.

The installation might seem straightforward, but paying attention to the nuances can save you potential headaches.

P Trap

If you notice a lot of extra piping under your basin, you will find the p trap. P-traps are named after their shape. They use a  bend in the pipe to trap water and seal. This seal prevents sewer gases and odors from leaking into your home. Now, we discuss the installation process of a P trap to install this type of trap.

At first, measure and cut the wall tube to the length required. Then, position the nut and washer on the wall tube. Insert the wall tube in the waste connector and tighten the existing nut. After that, connect the tailpipe with the strainer pipe and set the nut and washer on the tailpipe. Connect the P trap with the tailpipe and the wall tube. Tighten it with the existing nuts; finally, you have done the work.  

Waste P trap
Waste P trap

The removal process of a P-trap

You will need a bucket to catch water and a pair of water pump pliers to remove the P trap. First, remove the lock nuts that secure the P trap between the tailpipe and the wall tube. Doing it with the help of pliers will get a little bit of water. You should take the water in the bucket. After that, slide right down the P trap and remove it, and finally, you have done the work.

Bottle Trap

A bottle trap is used in a basin and sinks to prevent the entry of foul gases. The bottle trap looks like a bottle; you can easily clean it without removing the whole body. This trap is longer than the p and the s-traps. The installation process of a bottle trap is easy. Now, we discuss the installation process to do it easily in the future.

First, remove the outlet nut and place it over the waste pipe. Then, place the nut and the conical rubber washer on the waste pipe. Ensure that the chamfered edge faces the trap outlet. Then, place the trap outlet over the waste pipe and align the outlet nut to the thread. You will need to tighten it with your hand in the clockwise direction. To fix the trap to the strainer tailpipe, loosen the locking nut. The adjustment tube can then be set at the desired height once at the correct level. Then, connect the BSP nut to the waist and remember to re-tighten the lock nut. Finally, You have done the work.

The removal process of a bottle trap

The removal process of the bottle trap and p trap is nearly the same, so we don’t discuss it again. But you will find some advantages when cleaning a bottle trap. You will not need to remove the whole body. Just turn the base of the bottle trap counterclockwise until the bowl comes out. If you need to remove the whole body, you should first remove the base and wall tube.

washbasin mixer and bottle trap
washbasin mixer and bottle trap

The S-Trap:

The S-Trap, named for its distinct ‘S’ shape, is a classic fixture in plumbing, primarily used in areas where the waste outlet enters the floor instead of the wall. Although S-traps have a storied history, they are slowly becoming less common in modern buildings, mainly due to building codes that favor the P-Trap design. However, in many older constructions and specific settings, the S-Trap remains an essential plumbing system component.

Design and Mechanism:

The S-Trap features two significant curves, contributing to its ‘S’ shape. The primary function of these curves is to trap a small amount of water perpetually, creating a seal that blocks sewer gases from entering living spaces. Using gravitational force, the S-Trap effectively captures water in its curves as it flows down the drain.


Traditionally, S-Traps were widely used where the plumbing setup required the waste pipe to go through the floor. This is commonly seen in older buildings or particular types of commercial establishments.

Limitations and Challenges:

While the S-Trap effectively seals off odorous and potentially harmful gases, it has some limitations. For instance, the design is more susceptible to “self-siphoning,” where the water seal can be broken if water flows through it quickly, allowing sewer gases to escape. This flaw has diminished its use in modern plumbing systems, where P-Traps, less prone to self-siphoning, are generally preferred.

Codes and Regulations:

Understanding that S-Traps are not universally accepted in modern plumbing codes is crucial. Before installing an S-Trap, it’s advised to check with local building codes or consult a professional to ensure you comply.


Despite its limitations, the S-Trap is relatively easy to clean and maintain. Regular cleaning ensures that the water seal remains effective and minimizes the risks of clogs or leaks.

s trap and p trap
s trap and p trap

The unique basin waste trap

Floor Trap

The floor trap is located below the floor to collect wastewater from the basin. This trap is available in cast iron or UPVC material. It has removable grating (jali) on top of the waste trap. The water seal needs to be at least 50 mm deep. Now, we discuss the installation process of a floor trap to understand the process.

You will need a bosch concrete blade on a circular saw to install a floor trap. Before starting,  please wear a respirator to save yourself from the dust. To be sure that you plug into a GFI. You must see what’s happening underneath this floor and get started. Score around the edges of the drainpipe, then knock out the concrete with a hammer and tile chisel. After that, you should adjust the floor trap and reassemble the concrete. Finally, you have done the work.

Floor trap
Floor trap

The removal process of a floor trap

To remove the floor waste trap, you will only need a hammer. Then, hit around the trap cover slowly. After that, it will be easy to remove the floor trap, and finally, you have done the work.

Gully Trap

You will find a Gully trap outside the building. It collects the wastewater from the basin before going to the external sewerage line. This waste trap prevents the entry of cockroaches and other insects from the sewer line to the waste pipe. Now, we discuss the installation process of a gully trap so you will learn how to install this type of trap.

You will need to prepare the location to install a gully trap. If you want to install it in underground drainage, you should dig a hole in the ground. The upper part of the gully trap might remain at the ground level. Stiffen the place using concrete, then connect the sewage pipe to the gully trap. After that, pour concrete over the waste trap and connect the gutter drain to the rainwater gully. Before you do that, you will need to adjust the outlet size. Keep in mind that you will need to clean up the gully trap regularly. If you own a rainwater gully with a basket, clean it thoroughly before winter.

The removal process of a Gully Trap

At first, you will need to understand where the gully trap is situated. Then, score around the edges of the gully trap and take out the concrete with a sledgehammer. After that, disconnect it from all the drain pipes. Then you can remove it, and finally, you have done the work.

Gully Trap
Gully Trap

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