3 liters
In a modern toilet you use 13 litres per flush.
You use anywhere from 1 cup of water to 5 cups of water to flush the toilet. This is per time you flush the toilet.
It takes 1 bucket of water when we flush.
100 Galen
I believe it's 3 gallons
5 gallons
1.6 GPF.
There is about four to five gallons wasted if you flush a toilet but I don't believe that it makes a difference if the handle is loose or not. Unless, the toilet is leaking from the handle or somewhere else.
5 gallons
5 billion gallons per year
6/7 litres usually but you can change that by altering the stopcock level.