Dual-flush toilets, designed to save water, are more prone to leaks, so they end up wasting more water than they conserve, reports The Guardian.
Dual-flush toilets have been in use for years as an efficient alternative to help lower domestic water consumption. However, according to Andre Tucker, water efficiency manager at Thames Water, the water losses from toilets that continuously flow through the day and night exceed the amount of water that the dual-flush devices are intended to save. It is a growing problem as more people install this type of toilets when they retrofit old bathrooms.
The UK nonprofit NGO Waterwise estimates a leaking toilet could waste up to 400 litres of clean water every day. That would amount to a total of 400 million litres of water from UK toilets as a whole every day. They calculate that between 5% and 8% of all toilets leak, and most of those are toilets with a dual-flush mechanism.
The Bathroom Manufacturers Association (BMA) has admitted that the drop valve system used by most dual-flush toilets is more prone to leaks than the traditional siphon when not maintained, according to the BBC. One of UK’s major plumbing manufacturers, Thomas Dudley Ltd, told the BBC: "If we're serious about wasting water and we want to stop it, the only way to do that is put a siphon back in”.
Waterwise affirms that fixing the problem of leaking toilets could “contribute around 10% of the additional water capacity needed to cope with an extreme drought in England by 2050”.
Confusing flush buttons are also blamed for dual-flush toilets not achieving the water efficiency they are meant to. In fact, a survey done by Thames Water in 2019 revealed widespread confusion, with more than 75% of people getting one toilet’s flush function the wrong way around. “There are so many different types of toilet out there that it’s no surprise people don’t know which button to press. In many cases, what seems to be the obvious option for a shorter flush actually uses the most water”, said Tucker.
