NO-ONE knows how much water the kingdom of Saudi Arabia uses annually in its homes, factories and farms. Whatever the actual figure is, it far exceeds the amount that falls on the country as rain, on average less than 100 millimetres each year.

Urbanisation, industrialisation and the explosive growth of high-tech farming in the 1980s have put water demand on a path that worries anyone concerned with the long-term viability of the kingdom's economy. Analysts estimate that water use is growing at a rate of at least 10 per cent a year. If this is the case, consumption will have increased by 75 per cent in the past five years and is probably well in excess of 35,000 million cubic metres a year.

Rocketing demand is due to several factors:

Rapid urbanisation. The overwhelming majority of Saudi Arabia's population now live in conurbations

Industrialisation. The kingdom's big, new industries use huge amounts of water for cooling purposes

Agricultural development. A policy of subsidising inputs and credit for farmers coupled with protectionism and a wheat purchase programme have made water-intensive farming risk-free and highly profitable. No charge is levied on farmers for ground water used.

The rise in demand in urban and industrial areas has been given a further upward twist by the government's policy of keeping down tariffs. In March 1992, the council of ministers approved cuts in a range of service fees. The cost of water for smaller consumers was cut by 50 per cent.

The government is now struggling to deal with the consequences of the cheap water strategy. In urban areas, the Saline Water Conversion Corporation (SWCC) is implementing the region's largest water processing projects in an effort to keep up with demand. At present, there are 25 major SWCC units producing a total of almost 700 million g/d (gallons a day - equivalent to about 2.8 million cubic metres a day) of water.

Yet it is obvious to any resident that the supplies and the water delivery system are inadequate. Even in Saudi Arabia's largest cities, water is supplied for only part of the day to areas connected to mains water systems. Most houses have huge water tanks to store water at times when the supply flows. Many districts of the kingdom's conurbations are still supplied by water tanker.

Expansion

The response has been the launch of the largest desalination expansion programme for more than a decade. In 1993, the SWCC awarded contracts to build a 60 million-g/d expansion of the Al-Khobar desalination complex and a new 100 million-g/d plant in Shuaiba on the Red Sea to serve Jeddah, Taif and Mecca.

However, the SWCC believes this will only meet part of the projected demand rise in the 1990s. The agency has plans, if implemented, that would raise total desalination capacity to 1,350 million g/d in 2000. This would make the kingdom easily the world's biggest investor in seawater desalination systems. But the system would still only account for about 10 per cent of likely water needs. On present trends, the draw on ground water resources by the start of the new millennium will be even more intense than it is today.

For Saudi planners, the shift towards desalination and more mining of ground water is inevitable. However, alternative solutions have been offered. For two decades, leading figures, including former head of the SWCC Prince Mohammad al-Faisal, have advocated towing icebergs to Arabia from the southern oceans. There have been attempts by countries in the northern latitudes to export surplus water to the kingdom using empty returning oil tankers to carry it.

More recently, there has been growing pressure for conservation. In agriculture, the kingdom is trying to wean the farm sector off some of the most anomalous incentives to wasting water in an effort to reduce the draw on ground water reserves. Some Saudi experts are also demanding action to encourage households and factories to save water (see box). The pressure is on the government to apply policies that produce the water-saving results everyone now believes are essential.