In Beijing, water rates for home use start at just one yuan (about 12 cents) per cubic metre, far below cost, with heavy users paying a bit more.

ECONOMIST: China

Marin County cut urban water use from 170 to 143 gallons a head between 1987 and 1998 by a plan involving staggered water rates.

ECONOMIST: California's economy

The development of biofertilization techniques would also increase water use efficiency by promoting higher nutrient absorption and crop growth rates.

UNESCO: World Water Assessment Programme (WWAP)