Singapore’s prime minister, Lee Hsien Loong, told this water summit’s attendees that “water is a strategic necessity for Singapore” and so the country had “mobilized our machinery” in a holistic approach that includes investing in new technology and educating the public about water conservation.

SINGAPORE --- “Just turn on the faucet.”

That’s the answer most Americans and others in the developed world would give if asked how to get plenty of clean water. But for about two billion people, such a response is meaningless. These people – almost a third of the world’s population – do not have access to water that can be drunk without adverse health effects. An even greater number lack access to adequate sanitation, which is a principal reason that more than two million children die of diarrheal diseases each year.

Once upon a time, Matt Damon went for a long walk in rural Zambia. The devoted family man and method philanthropist was accompanying a 14-year-old Zambian girl who had no idea that her hiking companion was an Academy Award-winning international heartthrob.

In China, where large areas are chronically short of water and electricity, the mighty rivers that flow from Tibet into South and Southeast Asia are a tempting target. But as China dams more of its rivers in more places, neighbouring nations are worried that the next step may be to divert water on a large scale instead of just using it for power.

Now, when competing for Nile water, Cairo must deal with several governments and commercial interests. Moreover, Ethiopia...has announced plans to build a huge hydroelectric dam on its branch of the Nile that would reduce the water flow to Egypt even more.