In 1980 the Caroma company received a government grant to develop a duel flush toilet cistern. the new Duo set cistern had 2 buttons. Users could choose a big flush of 11 litres or a smaller flush of 5 litres and it worked well as the old larger cisterns. The toilet was tested in south Australian towns. The of residents all got a new free cistern and they saved 37000 litres of water per year.
In 1993 Caroma developed the 6/3 cistern which used even less water 6 litres for the big flush and 3 litres for the small flush. Caroma also redesigned their toilet bowls to make them work better with less water.
Caroma duel-flush toilets are now sold in more than 30 countries.