Public Toilets In Different Countries

Sustainability
The amount of water used in toilets is a significant portion of personal water usage, with an average of 90 litres (20 imp gal; 24 US gal) used per capita per day in 1990 in the United States. One system used to combat this is the "yellow mellow" system, in which a toilet is only flushed when it contains solid waste, and not only one person's-worth of urine. The custom is often described by the phrase "If it's yellow, let it mellow. If it's brown, flush it down." This system reduces the frequency of toilet flushing significantly.
Since 1990 new regulations and toilet designs have been aimed at reducing the amount of water used in each flush. Furthermore, dual flush toilets, developed in Australia, are in increasing use. A dual flush toilet has two flush options: one button or handle flushes the entire tank, for solid waste, and an alternate handle or button uses only part of the water in the tank, for smaller loads. Unlike the yellow mellow system, this does not decrease the frequency of flushes, but instead decreases the quantity of water used by flushing for smaller loads.