The Eco Cistem works in exactly the same way as a traditional cistern with the exception that it has an extra filling connection to allow a separate water source to be introduced (from the air conditioning unit).

Eco Cistem holds 18 litres – three times more than a conventional cistern – but its dual chamber design means it still fits like standard models.

The bottom chamber is adjustable in half litre increments to hold between 6 and 3.5 litres to meet different international requirements.

When flushed, the bottom chamber empties.

While doing so, a communication valve opens allowing condensate from the top 12-litre chamber to release into the bottom chamber ready for the next flush.

The upper chamber continues to be topped up with condensate ensuring an on-going supply.

It means that in hot climates where a huge amount of condensate is generated, mains water should never have to be used.

For back up, if there is an unusually high number of flushes in quick succession or the air conditioning is not in use, the cistern is filled in the conventional way using the mains water supply.