see Modern-day toilets come with two types of flushes, one is smaller than the other. They are called ‘dual flush’ toilets but ever wondered why are you given that option? We tell you.
here The concept of dual flush
THE CONCEPT OF DUAL FLUSH: The modern-day double flush toilets come with two different types of levers or buttons. One is larger, while the other is smaller and each button is connected to its own exit valve.
https://www.thejordanelle.com/cm8har9gj3 It is for water conservation
IT IS FOR WATER CONSERVATION: The larger lever is to flush out around 6 to 9 liters of water, whereas the smaller lever is to flush out around 3 to 4.5 liters of water. Clearly, the larger one is to flush solid waste and the smaller one is to flush liquid waste.
https://www.datirestaurante.com.br/xatryqw047 How much water do you save?
https://www.sabiasque.net/fb7rn13 
