New toilets in the USA are advertised and required to use no more than 1.6 gallons per flush (GPF) and some use 1.4 GPF or even less. Most new urinals with flushometers use 1 GPF or less.
Older toilets used from 3 to 6 gallons of water to flush. The new technology, most of which are now mandated by local and state codes use from 1.28 gallons to 1.6 gallons per flush. Additionally...