Increased awareness of water scarcity has prompted innovations in rainwater capture and a rethinking of toilet flush design. Delabie UK’s Eve Wellard looks at alternatives to cistern flush WCs which prevent unnecessary waste of potable water

We are all aware that water is our most precious resource, as we witness our rivers and waterways become increasingly polluted in the UK.

Unpredictable events can suddenly restrict available drinking water, as seen in May 2024 in Surrey when hundreds of homes were issued a ‘do not drink’ notice by Thames Water after excessive levels of hydrocarbons were detected, or up to 16,000 homes in Devon that were recently affected by an outbreak of the parasite cryptosporidium.

Research by Water UK found that “42% of UK adults are worried about parts of the UK running out of water in the next 25 years.” This isn’t at all surprising when we learn that the average person in the UK uses 142 litres of water a day, and a family of four could use up to 500 litres.

Vast quantities of drinking water, which must first be chemically treated and processed, are wasted each day through our toilet flushes. A standard cistern toilet releases up to 12 litres of water with each flush, and leaks are also a huge problem. Cisterns contain small plastic components that are vulnerable to rust and scale build up, quickly compromising the internal mechanism.

According to Thames Water, a small cistern leak causing the toilet bowl water to ripple wastes on average 600 litres of water per day, at a cost of around £483.99 per year.

In public and commercial buildings with high footfall, the potential for unreported leaks is extremely elevated. Five leaking toilets in a cinema for example, will waste up to one million litres of drinking water over the course of a year.

One solution to the problem of leaking toilets wasting valuable potable water is a direct flush system. Cisternless WC options use just 3 or 6 litres of water per flush, compared with the 12 litre flush of a cistern-fed toilet. The flush volume can be reduced even further if desired, to 2 or 4 litres, and the system connects directly to the supply pipe, minimising the potential for leaks.

Another advantage is that this system is compatible with grey water (rainwater, but also water from showers, baths, and sinks). Treating and supplying drinking water requires substantial energy and resources; using cisternless flush technology with grey water instead decreases the energy and chemicals required for water treatment, significantly reducing the environmental footprint. This also translates into lower water bills for consumers and operational savings for water utilities. Furthermore, less water needs to be extracted from natural sources, helping to preserve our rivers, lakes, and aquifers.

Rainwater capture can now be paired with innovative technologies such as direct-flush systems. An excellent example of the successful implementation of a direct flush system supplied with rainwater is the recent SuperLab project, by Robin Swailes Design & Development in Oxford.

Director of operations at Robin Swailes, Peter Okros explains: “The design used the entire roof area as a rainwater catchment to fill a 10,000 litre storage tank. The water coming from the roof is filtered three times as it enters back into the system, then pumped back into the toilets via separate pipework. 5 bar dynamic pressure is produced, more than enough to serve the cisternless toilet systems chosen.”

The specification reduces both drinking water consumption and utility costs, resulting in an elegantly designed, sustainable workspace.

Getting rid of the toilet cistern means that on average half a metre of usable extra space is gained in each WC; all components are within reach inside waterproof housing behind the control plate. Wall finishes can be completely streamlined, with no need to allow for an unsightly service hatch to access the stopcocks and inner mechanisms. Mounted to self-supporting frame systems, cisternless WCs are recessed within the wall and quick and easy to install, with minimal wall depth. This is key in the restricted context of a public washroom cubicle, giving architects greater freedom to create a spacious and inviting environment.

The firm’s managing director, Robin Swailes said: “You can service it through one aperture, everything’s there, and there’s no moving parts for assembly.”

As demonstrated by the SuperLab washroom installations, ecological soundness no longer needs to be at odds with the aesthetically beautiful. A cisternless flush system supplied by grey water promotes more efficient water use within buildings, without compromising on design or effectiveness.

Eve Wellard is marketing and communications manager at Delabie UK