Aircon condensate goes down the toilet

World fi rst as cistern uses air conditioning condensate to fl ush toilets, which is set to save UK hotels billions of litres of water a year.


he world’s fi rst cistern to use condensate from air conditioning units to fl ush the toilet has been launched and would save 218m litres of water a year for the 114 UK hotels currently being built.

Encore is the most environmentally friendly cistern as it uses a free, sustainable water supply that has previously been drained to waste. It could save UK hotels billions of litres of water because the cisterns can be installed in new buildings and retrofi tted.

Encore can be used globally and is also suitable for villas, apartments, offi ces and anywhere with toilets and air conditioning. In another fi rst for cisterns, Encore allows architects, consultants and specifi ers to secure two extra BREEAM credits – the gauge of how sustainability a building is.

Technical director at Encore, David Davis, said: “Air conditioning units have a pipe that drains away all the condensate.

“We’ve developed the only cistern in the world that uses this free water to fl ush the toilet. “When you consider how many buildings use air conditioning across the world, billions of litres of condensate water is generated, all of which has been wasted – until now.

“All buildings need toilets so why wouldn’t you use a cistern that recycles a free, sustainable water source, especially when there’s a global water shortage crisis?”

Water savings

There are 15,119 rooms in 114 hotels currently being built in the UK.

Compared to a traditional cistern, the average 132-bed UK hotel would save up to 1.92 million litres based on standard 80% occupancy levels. Encore would save them 218 million litres of water a year in total. For context, this would fi ll the equivalent of 87 Olympic swimming pools. What’s more, the water savings are even greater in hotter climates where more condensate is generated.

In the US, the 1,477 hotels currently in construction would save 4.7 billion litres of water

60 November 2017 David Davis with Encore cisterns.

a year, while the 302 in the Middle East would save 2.4 billion.

How it works

Encore holds 18-litres of water, which is three times more than a conventional cistern. However, due to its dual-chamber design, this means that it still fi ts in the same way as standard models.

The bottom chamber holds 6-litres, which comes from the mains pipe. Meanwhile, the upper 12-litre chamber is fi lled with air conditioning condensate.

The patented technology means the amount of water used in each fl ush is adjustable from six to 1.5 litres to meet diff erent international requirements.

When the toilet is fl ushed, the lower chamber is emptied and then refi lled with condensate from the upper chamber. If there are multiple fl ushes close together, or the air conditioning is not in use, the cistern is fi lled in the conventional way from the mains fed pipe.

If the toilet is not used for a while, surplus condensate is fed away.


Encore was invented by David Davis and Graham Kelly, directors of the UK-based G&H Group, a £25 million Building Services company formed in 1998.

Mr Davis said: “For decades we’ve designed and installed schemes and watched the stream of water produced by air conditioning units literally go down the drain, but not via the toilet. “Encore is a radical improvement on all conventional cisterns.

“Responsible businesses striving to construct the greenest buildings know BREEAM credits are very hard to come by.

“Gaining two for choosing an Encore cistern is simple and a great advantage.” Encore is as easy to fi t as a conventional cistern, compatible with industry standard rack mounting and there’s no expensive initial cost or long pay back period.

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