There are many different toilets . -Old style toilets used too use up to 20 litres per flush. New toilets in North America are now restricted to 13 or 6.5 litres per flush. many even have the choice,by which button you press.
the old style toilets use 5 gallons, the newer ones use 1.5 to 2 gallons
low flush toilets use less water.
Low flow toilets use 1.6 gallons per flush. The new(2014) ones are 1.28
they have toilets that use air rather than water. ~Jason
Old style toilets, (many of which are still in use) used up to 22 litres. New toilets are set to 13 litres, many with a 6 litre option.
Dual flush toilets usually use 3 and 6 liters of water depending on which way you push the flush handle - 3 liters for a little job and 6 liters for a major event. Single low-flush toilets use either 4.5 liters or 6 liters.
13 litres
Ideally 3.5 GPF
Composting toilets are considered "dry" toilets which use decomposition to eliminate waste as opposed to high pressured water. Further information about these toilets can be found on the Envirolet website.
Dual flush toilets use less water than traditional toilets. That means, less waste water to be treated. It doesn't reallyhelp the environment as we live in a biosphere and water is a renewable resource which is very easy to treat. It's really more greenwash.
Modern toilets use 1.28 or 1.6 gallons per flush
It depends on what type of flush you use. Old style single flush toilets use around 11 litres of water per flush, older dual flush toilets use 4.5 or 9 litres per flush, while modern water efficient dual flush toilets use 3 or 6 litres per flush.