It must be treated with respect, used sparingly and shared fairly with the poor, Al-Sabban said. And there is nothing to forbid water being recycled for irrigation or, if necessary, for human consumption.

Al-Sabban’s interest in the issue is the result of his work for the ministry, which is responsible for all of the kingdom’s 70,000 mosques. Since every Muslim must wash each time before he or she prays, these are among the biggest users of potable water. Al-Sabban discovered that each ablution involved several litres of water, creating an enormous source of demand and an equally vexing disposal challenge. His conclusion is that Muslims must be taught how the sharia provides an answer through conservation and restraint.

Science is the route being taken in Singapore. A blueprint for the Middle East was brought to the conference by the deputy director of the city-state’s Public Utilities Body, who glories in the name Major William Tong. From catching every litre of rain to turning effluent into branded bottled drinking water, Singapore has thought of everything. Tong showed how Singapore has bucked the global trend to reduce per capita water consumption.

As everyone knows, the Middle East is the world’s most arid region. Arabia is the largest landmass on earth without a continuously flowing river. The Arab world consumes every year much more water than it sustainably produces. Due to low or non-existent tariffs, theft, leakage and neglect, the region is in the early stages of a crisis that endangers the livelihood and lives of millions.

What is not so well known is that the region is at the same time producing a mass of effluent which is polluting its seas and contaminating the aquifers that supply the bulk of its water. Studies have shown that so much treated wastewater is being dumped in and around Riyadh that the city is beginning to sink in saturated soil. In Abu Dhabi, where hundreds of thousands of cubic metres of recycled water are used every day to irrigate thousands of farms and millions of trees, the water table is rising and salts and other damaging deposits are beginning to endanger the emirate’s green revolution.

Technology is providing an answer at both ends of the water cycle. The falling cost of seawater desalination has effectively eliminated the supply challenge in the wealthy countries of the Middle East. They will meet demand by building more water plants. And as Singapore has shown, sensible water pricing coupled with a social safety net can ensure limited renewable supplies can be made to last almost indefinitely.

The new technical frontier is disposing of raw sewage, some of which is disposed of in the most casual manner at the moment, and the treated effluent from treatment plants being built in growing numbers to cope with high rates of Middle East population growth and urbanisation. The answer may well be new technology using membranes to produce clean water at low cost in compact units that can be hidden and produce no odours.

In Oman, the largest plant based on membrane technology is now being built by Oman Water Services Company, which owns and operates the Muscat sewerage system. It is only a matter of time before other major public bodies adopt this groundbreaking system.

The marvel of the new water movement is that it is now possible for every single drop of effluent to be used in the farms, factories, offices and, dare I say, the kitchens, restaurants and cafes of the region. As Fady Juez, th