biggest consumer of water. Overall agriculture now accounts for about 75% of global water use (Gleick, 2004). Globally the number of irrigated hectares has almost doubled since 1960, with China, India and Pakistan accounting for almost all of that growth. The amount of irrigated area is falling per capita of the world's population, despite continuing to rise in absolute terms to 270 million hectares in 2001. The vast majority of this area is in Asia (190 million ha), with Europe showing a decline to 25 million ha in 2001 from a peak of 28 million in 1980. Elsewhere the irrigated area is stable. By volume, India, China, Pakistan and the United States together account for 75% of total agricultural usage. Data on agricultural usage are not reliable, as they are often severely underestimated for countries like India. If it is considered that the vast majority of this is under flood irrigation, which has an efficiency of at best 40%, then it is evident that a tremendous resource is not only going to waste but producing problems of aquifer exhaustion and soil salinisation. It also means that the economic productivity of this huge infrastructure that captures, stores and distributes water for irrigation is questionable. Historic overview Formal infrastructure systems for supplying water are almost as old as humanity. Between 16 000 and 10 000 years ago, agriculture developed and permanent settlements were established, requiring irrigation; hence, seasonal and other water shortages were experienced (Cosgrove, 2003). Reportedly the first major water infrastructure systems were constructed around 3000 BC by the Egyptians and the Sumerians. Around this time China was formally irrigating and by 2000 BC Egypt was maintaining large dams. In the period that followed, up to the birth of Christ, the Romans, Persians and others built major water supply and sanitation structures, some of which survive today. These advances were in response to urbanisation and the growth of towns and cities. Before major settlements, people followed