Down the pan05 August 2019

Having designed, built and installed power systems throughout their careers, two directors saw first-hand how water produced by AC units was going down the drain, so decided to spend a penny on a new system

Three years ago, a group of engineers were discussing building services work for a national chain of supermarkets. The group was tasked with the issue of transporting condensate from the centre of the store to a waste point. G&H Building Services Group MD Graham Kelly asked if the condensate generated by air conditioning units could be fed back into cisterns and used for flushing toilets.

“For decades we designed and installed schemes and watched the stream of water produced by AC units literally go down the drain, but not via the toilet,” he says. Encore (Environmental Condensate Recovery) was born, with Kelly and fellow director, David Davis (pictured), turning the idea into reality.

Encore can be installed into any building that has AC, including hotels, offices, apartments, leisure centre and airports. Performance figures from an office installation in North West England showed a standard cistern used 61,806m³ of water in the same toilet block, compared with two Encore cistern’s using 29,391m³, over the course of the past year. Average figures show a single Encore Cistern only using 14,695m³, which is four times less potable water than a standard toilet. Water savings are said to be even greater in hotter climates, where more condensate is generated.


While traditional cisterns only have a maximum capacity of six litres of mains-fed water, Encore holds 18 litres incorporating the collected condensate.

The cistern has similar dimensions to a traditional concealed unit, with an increased height to accommodate the additional water volume. To offer global appeal, the flush volume is adjustable in half litre increments to discharge between 3.5 and six litres.

When an Encore cistern is flushed, only condensate from the bottom chamber is used. While doing so, a communication valve opens, allowing the stored condensate from the top 12 litre chamber to refill the bottom chamber. The upper chamber continues to be topped up with condensate, ensuring an on-going water supply. If there is a high number of flushes in quick succession, or the AC is not in use, the cistern is filled in the conventional way using the mains water supply.

Installation is relatively simple. Instead of the condensate pipe connecting to the waste pipe, it is attached to the Encore cistern that features an extra inlet valve. There is no disruption to business operations during installation, and it doesn’t require any specialist maintenance, training or servicing.

“All buildings need toilets, so why wouldn’t you use a cistern that recycles a free, sustainable water source,” says Davis.

Furthermore, Encore allows engineers, architects, consultants and specifiers to secure two extra BREEAM or LEED building sustainability credits. This can assist designers in achieving a higher BREEAM rating or allow more costly solutions to be replaced with a more economical Encore cistern.

David Davis

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