As swimming-pool suburbia spreads across the desert sands of the booming Persian Gulf, developers and governments are wrangling with a major problem: There is almost no fresh water here.
The skyrocketing costs of desalination plants, long used as the source of most water, is leading governments to look at a possible cheaper source -- the wastewater from sewage plants.
"Is it dirty? Yes. But if it's properly treated, it is valuable," said Fady Juez, managing director of Metito, a Sharjah-based company that designs water and sewage treatment plants.
Juez was among the experts from some of the world's driest countries who gathered for a recent conference in the United Arab Emirates' capital of Abu Dhabi to seek ways to reuse the contaminated water that flows through their sewers.
The Arabian desert may be rich in oil, but it boasts not a single river.
Despite that, construction booms and government policies of providing free city water have pushed per capita consumption to the highest levels in the world: Water is lavished on golf courses, gardens and fountains, even as groundwater in overtaxed aquifers grows salty and unusable.
All Middle Eastern countries except Iraq and Syria face severe water shortages in coming decades, according to presentations given at the conference.
"We are the driest part of the world," Juez said. "And we are multiplying like mad."
To compensate, Gulf countries have traditionally turned to desalination, which provides some 60 percent of the region's needs. But such treatment plants are expensive and consume a lot of energy.
Supporters of using wastewater say it can be rendered so pure that it can be drunk -- or even used for Muslim ablutions, the pre-prayer ritual washing that requires an even higher level of cleanliness.
Most wastewater here gets cursory treatment before being dumped into the sea or poured into the desert. Only about 1 percent is recycled for farming and landscaping, mainly in the Emirates, Qatar, Oman and Kuwait.
Even if people balk at drinking or washing in treated sewage, participants said recycled wastewater could quickly be redirected toward irrigation and air conditioning, or at least re-injected into aquifers to improve groundwater.
Spend another 10 percent on a treatment plant and wastewater can be made suitable for irrigation, Juez said. For 20 percent more, you can drink it.
Singapore recently opened a treatment plant that uses ultra-fine membranes to convert city sewage into drinking water marketed as NEWater. The plant has become a popular tourist site.
In Saudi Arabia, a Muslim sheik is pushing for the recycling of water to become a religious duty. Ahmed Sabban, a deputy minister in the Islamic Affairs Ministry, requested and received a pair of fatwas, or religious edicts, from the kingdom's Islamic authorities that allow mosques to recycle water and use it for ablutions.
"Right now only 2 percent of our water is recycled. That is very bad," said Sabban, who spoke at the conference.
Since the ruling, Sabban said a pair of mosques in Jiddah have installed systems that recycle ablutions water -- after it is used for ablutions -- into the toilet system and then to irrigate the grounds.
Wastewater in Jordan is already filtered and recycled through the country's drinking water reservoir.
Kuwait's huge new Sulaibiyah treatment is the world's largest reverse osmosis plant, which filters sewage to standards higher than those governing drinking water in the United States. But that water is currently used only for irrigation, said George Labib, general manager of the country's major utility company.
Saudi Arabia is in the midst of implementing a $5 million project for water reuse and plans to spend another $50 billion on water over the next 25 years, said an official with the Water Ministry, Abdul Aziz Jaber.
With 5 percent of the world's population, the Middle East has just 1 percent of the world's accessible fresh water.
But past efforts to convince people in the region not to waste water were frustrated by governments' insistence on giving away the precious commodity, or selling it so cheaply that customers had no idea of its value.
"At least let them know how much it costs," Juez said. "Send them a bill. Tell them, 'You used $150 of water this month,' even if you don't charge them."