You may not pay it much thought, but every time you flush the toilet you could be pouring money down the drain. Pulling the chain accounts for a third of all the water we use in our homes and that can add up to a hefty water bill, as well as being extremely wasteful.

This is why not-for-profit environmental organisation Waterwise urges everyone to think before they flush and to use cistern displacement devices to save water. Better still, it says, the wasteful public should consider upgrading their toilets to new water-efficient models.

Waterwise also welcomes charity WaterAid’s campaign to raise awareness of the 2.6 billion people – 40 per cent of the world’s population – who do not have somewhere safe, private or hygienic to go to the toilet.

More than seven million of the toilets in the UK use a whopping 13 litres of water with every flush, so Waterwise are challenging everyone to reduce their water wastage. In order to do so, you can fill up a one-litre water bottle and place it in your cistern or write to your local water authority to claim a free displacement device. These methods will reduce the amount of water used in every flush, cut back your water bill and help the environment.

Unfortunately most of us have no idea how wasteful our daily trips to the loo really are or remember that high-quality treated drinking water is used for flushing. The average person flushes five times a day. By saving just one litre per flush, a typical household can save about 20 litres of water a day, according to the director of Waterwise, Jacob Tompkins.

“As much as 3 per cent of the UK’s energy is used for treating and pumping water and one-third of this is flushed down the toilet. So reducing water used for toilet flushing saves energy as well as water and helps you reduce your carbon footprint,” he says.

The UK has slowly become a nation of water guzzlers as our water consumption has been rising annually since the 1930s. There are some 45 million toilets in UK homes, using an estimated two billion litres of fresh water every day, while toilet flushing accounts for the second largest proportion of water use in the home – 30 per cent of the average house-hold’s water use.

It could pay to upgrade your toilet, as an old-style single flush toilet can use up to 13 litres of water in one flush. New, more water-efficient dual-flush toilets use only six litres for a full flush and four litres with a reduced flush.

The key to water efficiency is reducing waste, not restricting use. Each person in the UK currently uses 150 litres of water every day. It is easy for us all to reduce our water waste by around 20 per cent at little or no cost, says Tompkins. Turning off the tap when you brush your teeth can save as much as 6 litres of water a minute and a cistern displacement device in your toilet will save water every time you flush.