Bath waste system buying guide

Bath waste system buying guide

Jeremy, construction site supervisor, Cardiff

Guide written by:

Jeremy, construction site supervisor, Cardiff

132 guides

A bath waste kit assures the evacuation between the bathtub and the exhaust system. Composed of a bung, a drain, seals and connected to the PVC pipe, an waste system also includes a stopper - chain stopper, plug or shutter - and an overflow to avoid any surprises.

Important features

  • Diameter
  • Overflow
  • Bung
  • Type of closure
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Why equip a bathtub with a waste system?

Let's take you  bathtub. You should be able to take both a shower or a bath in it, as you desire. It is therefore necessary for the waste system to allow a rapid evacuation of the water as it flows from the shower column and to it ensures the proper seal, so that the bath fills.

Also, if you forget to shut off the water when preparing your bath, the waste kit must also be equipped with an overflow so as not to flood your home. A good waste system should successfully fulfill all these roles.

Elements of a bath waste system



The trap is the visible element at the bottom of the bathtub. The bung integrates the bath with the drain (placed underneath). In most cases the installation is as easy as screwing it in. The trap is mounted on a washer.


The drain has two primary functions. The first is to trapmaterials and waste that could have fallen into the bathtub, preventing their entry into the pipes. The second is to avoid, thanks to a water guard, any bad odors that may try to come up to the bathroom.


It is often a latch system that will plug or unplug the bung, thus allowing the bath to be filled or emptied. It can controlled by a knob, pull, cable or chain. There are also manual shutters (rubber stoppers equipped with a chain) and simple force shutters, where you simply have to press with your feet.


It is a safety feature in case you forget to cut the water, doing it for you and avoiding a potential flood. The overflow is connected to the drain, usually by a flexible hose.

There are a multitude of shapes, materials and volumes of bathtubs. However, they all have so-called "standard" dimensions when it comes to the discharge, the position of the overflow and the length of the sealing system. The dimensions are as follows:

  • Between vertical bung and overflow = 400 mm;
  • Between horizontal bung and overflow = 200 mm;
  • Length of overflow tube = 54 to 130 cm;
  • Drain with water guard greater than or equal to 50 mm.

When choosing your waste system, make sure that the model you have chosen is standard or universal.

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What are the different types of waste systems?


Different types of bath waste systems are available to provide all the required functions. They are all composed of at least one bung, one drain and one overflow pipe. The difference between the models is the shutter's control mechanism:

  • The conventional system consists of a cableconnected to a leveron the bung opens or closes the flow. The cable is connected at the other end to the knob or pull-cord;
  • The system with automatic closing allows for the opening or the closing of the flow with a simple pressure of the foot on the bung, referred to as "force closing";
  • The manual system where the seal is provided by a rubber stopper equipped with a metal chain.

Depending on your bathtub (whether or not it has a shutter control), orient your choice to the appropriate system. You can, however, choose an automatic dump system even if your bathtub is equipped with a knob.

What are the factors to consider when choosing a waste system?


If your bathtub is of the standard dimensions, the different measurements should not represent any difficulties since they are all identical. Nevertheless, it would be good to be aware of the following features.

Characteristics of waste systems

Bath drainage diameter

  • 90 mm
  • 60 mm
  • 50mm

Overflow type

A conventional overflow will require an waste system that includes a pipe to be connected on one side to the overflow and on the other to the drain.Built-in overflow: some bathtubs have an overflow pipe embedded in the configuration, who's outlet is directly to the side of the main drain hole.

Sealing system

  • Manual shutter with stopper and chain.
  • Shutter controlled, with knob or pull.
  • Automatic shutter.

Ground clearance

This point is very important because it determines the space available between the bottom of the bathtub and the floor. This may or may not foprce you to purchase an ultra-flat waste system. As a rule, the minimum recommended space is 13 cm.

Diameter of the evacuation

Here again, this parameter is standard. A bathtub drainage is made of PVC 40 mm. Moreover, the majority of waste systems available on the market offer a 40 mm output.

Installation advice


A clogging or blocage may always occur. It may be because of waste, hair or an object that got past the bung. It may also be that the flow is no longer correct.

This is why the standards impose access to the waste system through a access panel. This panel must be located at the horizontal level of the drain, thus facilitating maintenance and possible dismantling.

Some kits come with inspection hatches, of various dimensions and color. The important thing is to choose a hatch that is lockable to prevent any risk.

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Access panel

More information

For any DIYers in full bathroom renovation mode, or bath-tub lovers who want to upgrade, follow the links below for bathroom-related accessories, advice from our editors and more helpful guides:

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Guide written by:

Jeremy, construction site supervisor, Cardiff, 132 guides

Jeremy, construction site supervisor, Cardiff

Electrician by trade, I first worked in industrial estates where I installed, wired and fixed a large number of electrical installations. After this, I managed a team of electricians for this type of work. 10 years or so ago, I turned to building and construction. From the modest family home, to gyms and theatres; I have been able to coordinate, audit and organise all sorts of construction sites. for 4 years now, I am restaoring and bulding an extrension to a bungalow in the heart of the welsh countyside. My experience in manual work and my knowledge means I am proud to be of service. Terraces, interior design, roofing, plumbing, electricty, anything goes! We have, my wife, daughter and I, built almost everything we have from scratch! So to answer all of your questions, and to orientate and advise you on coosing your tools? Easy!

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