Are Water-Saving Toilets Actually Wasting Water?

Dual-flush toilets, which were specifically designed to be more efficient, are actually wasting more water than they save. That’s the message from Thames Water, the largest water company in the UK, who say that a high incidence of leakages among newer models mean that around 400 million litres of water are being wasted every single day.

That’s a huge waste of one of the world’s most basic yet most precious commodities, especially given the critical importance of water to the agricultural industry and the very real prospect of the UK experiencing unprecedented drought in coming years due to climate change.

A busted flush

The dual-flush model was initially introduced to make it easier for consumers to conserve water by selecting the smaller quantity option when flushing the toilet. This generally releases four litres of water (as opposed to six in the larger quantity) and was intended to save the country millions of litres per day.

As things have turned out, however, it appears to be wasting that figure instead. That’s because approximately 5% to 8% of all toilets are prone to leaking within a short period after installation, and the majority of those are dual-flush models. The 400 million litres lost on a daily basis would be enough to meet the needs of 2.8 people Britons, or the combined populations of Belfast, Bristol, Cardiff, Edinburgh, Liverpool, Manchester and Sheffield.

Drop valve vs syphon

The fault lies with the drop valve system incorporated into the newer models. These function via a valve located at the bottom of the cistern, which is opened when the flush is depressed. However, debris, wear and tear or other issues can interfere with the mechanism and jam it open, meaning that the toilet is effectively flushing continuously throughout the day.

By contrast, more traditional models use a syphon system. With these, the valve is located higher up on the cistern wall, so that water can only flow out of it and into the bowl once it has reached a certain level. Because the valve is generally located above the water level, there is less chance that it will become damaged or rendered ineffective, meaning older models are often more efficient.

Returning to old ways

One solution to the conundrum could be a transition to completely waterless toilets. One such model has been developed by the Bill and Melinda Gates Foundation and dispenses with water entirely, instead filtering out waste into its liquid and solid constituent parts, then sending these off to be recycled.

While that might sound like an ideal answer to the problem, the technology is still some way away from becoming commercially viable. In the meantime, plumbing experts have suggested a return to old ways could be on the cards. “A siphon will not leak whereas an outlet valve – if we look at the figures we’ve got – they could leak within a week of installation. It could be two years but they will leak,” argues Jason Parker, MD of Thomas Dudley Ltd, a leading plumbing firm in the UK. “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.”