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How Toilet Cisterns Work: Beginners Guide



V Susan
Hi! I'm Susan. I am passionate about woodworking, general DIY and home improvement. If you'd like to connect with me or talk about something you like at mellowpine, drop me a mail at susan@mellowpine.com


Toilet Cistern

A toilet cistern is the water storage tank on the toilet, and when you flush the toilet, this water is released and used to flush away waste. The fill valve refills the cistern for the next use. Different types of toilet cisterns include gravity-fed pressure-assisted, dual-flush, and single-flush systems.

Toilet cisterns can be made from various materials, but they all need to be able to hold enough water to flush the toilet.

They can be round or square, and you can mount them on a wall or place them on the floor.

This article explains how a toilet cistern works.

I’ll also discuss the various types of cisterns available.

How Does a Toilet Cistern Work?

Parts of a Toilet Cistern
Parts of a Toilet Cistern

Toilet cisterns are an important part of any toilet and play a vital role in flushing.

When you flush the toilet, the cistern releases a predetermined amount of water into the bowl to flush away waste.

All types of cisterns operate on the same fundamental principles.

The cistern connects to the bowl with a fill valve and a flush valve, typically positioned above the toilet.

This fill valve regulates the amount of water pumped into the cistern from the main water supply.

Excessive water leads to constant running, while insufficient water results in inadequate flushing.

Flushing the toilet directs water from the cistern into the toilet bowl through the flush valve.

Most toilets have a handle on the side of the cistern that triggers the flush valve when you push it down.

The handle lifts a rubber stopper out of the way, allowing water to gush out of a small hole and into the bowl below.

Common Toilet Cisterns

Toilet cisterns are usually one of the four types.

Gravity Fed Cisterns

Gravity Fed Cistern
Gravity Fed Cistern

Gravity-fed cisterns rely on gravity to move water from the tank to the bowl.

These cisterns are typically less expensive than pressure-assisted models, but they can be more prone to leaks.

Clog-freeProne to odors and leaks
CheapRequires 2-3 flushes for heavy waste
Causes skid marks on the bowl
Prone to sweating
Pros and Cons of Gravity-Fed Cisterns

Pressure Assisted Cisterns

Pressure Assisted Cistern
Pressure Assisted Cistern

Pressure-assisted cisterns use a pump to force water from the tank to the bowl.

These models are typically more expensive than gravity-fed cisterns but tend to be more reliable and less likely to leak.

Powerful flush with less waterQuite noisy
Less prone to sweatingCostly to acquire and install
Best choice for commercial settings
Pros and Cons of Pressure-Assisted Cisterns

Dual Flush Systems

Dual Flush System
Dual Flush System

Due to their environmentally friendly design, dual flush systems are quickly gaining popularity.

When you need to flush different types of waste, two buttons will be on the same unit.

A full flush is for removing both solid and liquid waste, and a partial flush is for removing liquid waste only.

Water conservation is the primary benefit of a dual-flush toilet.

Many countries mandate this type of toilet to conserve water.

Cheap since it conserves the waterFlush buttons are prone to getting stuck
Environment-friendlyA defective flush valve could lead to constant running of the toilet
Stylish and attractive
Pros and Cons of Dual Flush Systems

Single Flush Systems

The most common type of toilet found in older homes and buildings is the single-flush toilet.

In a single flush system, the amount of water used will be the same irrespective of liquid or solid waste.

These toilet systems typically employ a trip lever handle mounted on the tank’s side or front.

A lift chain connects the toilet handle to a flapper.

Pulling down on the toilet handle lifts the flapper off the flush valve, allowing water to flow down to the bowl and flushing to occur.

However, they use significantly more water than their alternatives, making them less environmentally friendly.

Visually appealingConsumes more water(1.6 gallons per flush)
Low maintenance costsHarmful to the environment as it uses more water
Easy to find replacement parts
Pros and Cons of Single Flush Systems

Can a Toilet Work without a Cistern?

Toilet without a Cistern
Toilet without a Cistern

Yes, a toilet can work without a cistern.

Tankless toilets function with a water supply line that provides water at a higher pressure.

This allows the toilet to flush human waste through the drainage system with just one flush.

Tankless toilets, along with pumps or other technologies that power the flush, can help in buildings where water pressure is low, such as in most private homes.

These toilets adopt a two-valve system to achieve the ideal flush.

The high-pressure valve controls water flow into the system from the main supply.

In contrast, the low-pressure valve controls the pressure of water entering the toilet bowl.

Why Should You Clean a Toilet Cistern?

It is crucial to clean the toilet cistern regularly as it can become filthy over time.

Cleaning the tank twice a year is ideal.

The purpose of toilet cistern cleaning is to remove filth and bacteria that can lead to illness.

How to Replace a Toilet Cistern

A faulty toilet cistern may require replacement. Replacing a toilet cistern is not difficult and can be done in a few simple steps.

  1. First, stop the water supply, and close the valve behind the toilet. To empty the water in the cistern, flush the toilet.
  2. Remove the old cistern by unscrewing it from the wall or floor. If your cistern is attached to the wall, you will also need to disconnect any pipes connected to it.
  3. Ensure that the new cistern is installed in the same location as the old one. Turn on the water supply after tightening all connections.
  4. Turn on the water and flush the toilet to ensure that everything is working.

How to Troubleshoot a Toilet Cistern

You can try a few things to fix your toilet cistern if it isn’t working properly.

Start by turning on the cistern’s water supply. Try flushing the toilet to see if water enters the cistern.

If it does not, it could be due to a problem with the float arm or ballcock assembly.

Simply adjust the float arm until it is in level with the water in the cistern.

If your cistern still does not fill with water, the fill valve may be faulty.

To begin troubleshooting, shut down the water supply to the cistern.

Then flush the toilet while holding down the handle to drain the tank completely.

Remove the cistern lid and check if the fill valve is open. If it isn’t, rotate it counterclockwise until it is.

Connect the water line and flush the toilet to see if water flows into the cistern.

If your cistern still does not fill with water after following these troubleshooting tips, call a plumber for assistance.

Frequently Asked Questions(FAQs)

Does a Toilet Cistern Smell?

Strange smells emitted from the toilet cistern are a common problem in many households.

This is because of the stagnant water in the tank, and it will continue to stink out of your bathroom until you clear the problem.

Use vinegar and water to scrub down the inside of the cistern and rinse with clean water.

Will any Cistern fit any Toilet?

Cisterns come in various sizes, shapes, and designs to suit different toilets.

Choosing the right cistern for your toilet is important to ensure it flushes effectively and doesn’t leak.

You’ll need to consider the size of your cistern when choosing a new toilet or having a new bathroom fitted.

What is the Cost to Install a Cistern?

The installation cost depends on whether it is a DIY project or a plumber’s job.

Depending on the complexity of the job, the average cost to install a cistern ranges from $100-$500.

V Susan
Hi! I'm Susan. I am passionate about woodworking, general DIY and home improvement. If you'd like to connect with me or talk about something you like at mellowpine, drop me a mail at susan@mellowpine.com