Air conditioning condensate used to flush toilets

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Published: 11 July 2017


cistern condensate air conditioning
David David of G&H Group with the condensate cistern
A UK building services company has launched what it says is the world’s first cistern to use condensate from air conditioning units to flush the toilet.

Directors Graham Kelly and David Davis of the G&H Group created Encore, which uses a free, sustainable water supply that until now has been drained to waste.
​Data from hotel benchmarking specialist STR shows 15,119 rooms in 114 hotels are currently being built in the UK. Compared to traditional cisterns, using Encore would save each hotel 1.92 million litres a year based on standard 80% occupancy levels.

In total, Encore would save them 218 million litres of water, which for context would fill the equivalent of 87 Olympic swimming pools a year. And the water savings are even higher 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 a year and 2.4 billion litres for the 302 hotels in the Middle East. It will also allow those specifying to secure two extra BREEAM credits and LEED points.

David 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. 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. Encore is a radical improvement on all conventional cisterns.

“Responsible businesses striving to construct the greenest buildings know BREEAM credits and LEED points are very hard to come by. Gaining two for choosing an Encore cistern is simple and a great advantage.”

Encore is aimed at those building and refurbishing hotels, villas, apartments, offices and anywhere with toilets and air conditioning. The patented technology means the amount of water used in each flush is adjustable from six to 1.5 litres to meet different international requirements.

“Air conditioning units have a pipe that drains away all the condensate,” said Mr David. “We’ve developed the only cistern in the world that uses this free water to flush the toilet. All buildings need toilets so why wouldn’t you use a cistern that recycles a free, sustainable water source and immediately saves money especially when there is a global water shortage crisis?”

How it works
  • Encore holds 18-litres of water which is three times more than a conventional cistern but its dual-chamber design means it still fits like standard models.
  • The bottom chamber holds 6-litres, which comes from the mains pipe.  
  • The upper 12-litre chamber is filled with air conditioning condensate.
  • When the toilet is flushed, the lower chamber empties and refills with condensate from the upper chamber.
  • If there are multiple flushes close together or the air conditioning is not in use, the cistern is filled in the conventional way from the mains fed pipe.
  • If the toilet is not used for a while, surplus condensate is fed away.