Alt-Energy Blog points us to an article about the use of solar powered water purifiers on the island of Kulhudhuffushi, in the Maldives. Starting in January, 2005, a set of off-grid systems will start producing bottled drinking water for the island's inhabitants; the government of the Maldives has identified twenty some islands as candidates for these systems.
The units use solar power to draw the water up from brackish sources below the surface and pass it through a system of reverse osmosis units to remove all pathogens, metals and dissolved solids, using just 20% of the power of a standard reverse osmosis unit.
Each unit can produce 500 litres of water per day from a single 100 Watt (1 square metre) solar panel.
Solar Energy Systems Infrastructure, the company making the systems for the Maldive government, plans on introducing the technology to other off-grid islands in Indonesia and the Philippines. One would presume that being on an island is not a prerequisite for the use of this technology; any location with a combination of brackish water and abundant sunlight would suffice. As access to clean water is far and away the most important development issue around, leapfrog technology like this could indeed be worldchanging.