Toilet flush buying guide

Toilet flush buying guide

Arnold, Researcher / handyman, Birmingham

Guide written by:

Arnold, Researcher / handyman, Birmingham

10 guides

Essential to every toilet, flush systems allow wastewater to flow from the toilet pan. These cost-effective systems often combine a fill valve, a float and a flush valve in one and investing in a new mechanism should put an end to leaks. Here's our guide to help you find the right flush for your toilet!

Important features

  • Type
  • Fill valve
  • Size
  • Float
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Choosing the right flush for your cistern

In order to choose the right flush system, you will have to look at your cistern and take note of some measurements. Rest assured this process is fairly straightforward and shouldn't take more than five minutes!

  • Measure the hole in the cistern lid (b) where the flush button will be installed (the diameter should range from 16 to 50 mm).
  • Use your tape measure again to check the height of your cistern (d) (this should generally measure between 262 and 392 mm).
  • While often standard in size, check the diameter of the outflow hole (b) of your cistern (this should measure 60 mm... in theory!).
  • Although not strictly a measurement, you should also check where your fill valve is located (c) (either below or on the side of the cistern).
  • Many systems are sold with floats. If your float still works well, there is no need to change it. In this case, you should ensure you only purchase the valve system.
  • Fill valves have an adjustable base, allowing you to alter their height beneath the cistern lid.
  • You can also choose between a single or double flush button – bearing in mind that dual flush models are less wasteful!

Toilet flush parts and assembly


Flush operation


The toilet flush is simply the system that allows wastewater to be removed from the toilet pan and be replaced by clean water.

Its basic operation centres around a certain amount of water being released from the cistern in one go. This volume of water creates a flow that carries away the waste and toilet paper.

The cistern, or toilet tank, is connected to a water supply hose at one end and the toilet bowl at the other. It also contains the toilet's key component: the flush mechanism, which is used to regulate the inflow and outflow of water in the system.

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Different types of toilet flush mechanism

Nowadays, flush systems are installed directly above the toilet pan – gone are the days when cisterns would have to be installed two metres above the pan and operated by a pull chain!

The control used to operate the flush system is found at the top of the cistern. There are several different control types: lever handles, pull handles, single push buttons and dual push buttons.

Flush control: pull handles or push buttons

  • Pull handles: These controls require you to pull up a metal rod to open the flush system and release water from the cistern into the toilet pan. This system is generally considered outdated as it does not allow you to control the amount of water released with each flush.
  • Single push button: A much-improved option, this system allows for better control over how much water is released. It is sometimes even possible to stop the flow of water once the bowl has been cleared of waste, without having to wait for the cistern to empty completely.
  • Dual push button: The most advanced control of all, this system consists of two buttons: one small and one large. Pressing the small button will release less water than using the large button. This will help you to save water – after all, there's no need flush away waste with twelve litres of water when six would do! Additionally, you can even adjust the volume of water released when using the smaller button.

Connecting the push button to the flush mechanism


The dual push button sends information to the rest of the mechanism through a control system. There are several different possibilities:

  • Cable: the push button (or pull handle) is connected to the flush mechanism by means of a cable. The advantage of this system is that you can access the cistern without having to remove the button. This mechanism is also compatible with remote flushes (which can be installed to the side of the toilet lid). 
  • Mechanical control: the push button or pull handle is connected directly to the flush mechanism. This advantage of this system is that it tends to be more durable. It also allows you to easily adjust the amount of water released (when using push buttons). The biggest drawback of some pull models is that you have to remove all or part of the button to lift the cistern lid and their use is usually restricted to the hole found in the middle of the lid.

You can also opt for a combination of cable and mechanical control, allowing you to take advantage of both system types.

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Flush system

Different types of fill valves and toilet floats

Toilet fill valves 


The cistern is linked to the water network of your home by a special valve.

This fill valve is connected either below or on the side of the cistern. It is also attached to a float and a flush valve designed to stop the cistern from filling once it contains a certain volume of water.

Side-entry fill valve  


This type of fill valve is connected to the side of the cistern and tends to be quite noisy as water flows on the surface. Side-entry fill valves feature a screw that comes in a standard size (12x17) and these are generally made of chrome-plated brass.

Bottom-entry fill valve


Bottom-entry toilet fill valves send water into the cistern from below, meaning they make little or no noise when filling up. The fill valve is connectedto a flow control device equipped with a float.The float shuts off the valve when the water in the cistern reaches a maximum level.

Toilet floats


Toilet fill systems are generally supplied as a fill valve and float in one single part. There are two main types of float:

  • Float ball valve: the float shuts off the valve via a lever to stop the flow of water.
  • Float cup valve: the float rises along an axis or track shutting off the valve to stop the flow of water.
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Installing and maintaining your flush mechanism


Making sure your flush mechanism is in perfect working condition will end up saving you money in the long term. Do not ignore any leaks or faulty parts as this will end up increasing your water bill.Most leaks are caused by seals that are in poor condition or covered in limescale.Take care to clean your flush mechanism regularly – especially if you live in an area with hard water. Limescale can build up the joints of the mechanism and can affect the seal between the cistern and the toilet pan.

Flush systems are very easy to install; this should be a very straightforward task as long as you follow the assembly instructions and choose the right model for your cistern. While many flush mechanisms come in standard sizes and can be adapted to fit any type of cistern, you should still measure your tank before buying a new flush.

Lastly, please ensure you cut off your water supply before attempting to remove your toilet flush!

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More information

For more advice on bathroom renovation, check out our editors' other guides: Bathroom sink buying guideShower enclosure buying guideToilet buying guideHow to decorate your bathroom

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Guide written by:

Arnold, Researcher / handyman, Birmingham, 10 guides

Arnold, Researcher / handyman, Birmingham

A chemist by training and a self-taught handyman, I work in the pharmaceutical industry. As a young dad of 36 years, tinkering is like breathing to me: in short, I am a jack-of-all-trades. To my credit, I have already completed 5 kitchen installs, a renovated apartment, and an extension on my own house (for financial reasons, my wife and I have chosen the closed-cover option for wooden house extension). Over the last three years I have done everything: insulation, plasterboard, electrical, patching, painting, parquet, dressing, bathroom, short, 60 m2, made entirely with my own two hands. Fortunately, I have my own personal decorator. I don’t worry about styles and colors. As they say: happy wife, happy life. My motto: good tools and good products are half the work, the rest is patience and meticulousness. To your keyboards. The good advice is here.

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