People skeptical of hearing water experts talking about water crises put their faith in the human capacity to innovate. They point to the rapid decline in costs of taking the salt out of sea water as evidence that – when we really have to – we will innovate and make sure we can meet our water needs.
Necessity is the mother of invention. Israel, one of the driest countries in the world, has invested heavily in non-conventional sources of water. Desalination currently provides around 40 percent of Israel’s municipal water supply and the plan is for this source to provide 70 percent by 2015. In March, a team from the the World Bank's WDR2010  and Middle East North Africa units visited the largest operational reverse osmosis desalination plant in the world, in Hadera.
Desalination does indeed have potential to meet the municipal water needs of many people in the world – but only those who live near the sea.
Uri Shamir, Professor Emeritus at Technion on 'Desalination'  from World Bank  on Vimeo .
Costs have come down to about $0.55 per cubic metre, about half what it was a decade ago. How have engineers managed this? Economies of scale are important. They have also been able to save on costs by designing an efficient system within the plant and by clever energy saving technology. Will the costs come down much further? About 10% say the Israeli experts. Not more.
Israel’s very careful management of every drop of water has led to an interesting problem.
Until a few years ago, the desalination plants had levels of boron, an element that occurs naturally in the seawater, that were safe for human consumption. But when that desalinated water was re-used in agriculture, especially in drip irrigation systems  that concentrated the water at the roots of the plants and involved limited flushing of the soil, the boron levels built up in the soil so much that they harmed the plants. Now, the desalination plants have an extra unit to remove the boron. That adds 10% to the costs of desalinating the water. Other countries have learned from the Israeli experience and are beginning to limit their boron concentrations in desalinated water as well.
Clearly, then, innovation has brought a great boon for water supplies for those who live near coastlines and we can expect to see more plants built. Innovations allowing the use of renewable energy sources to power desalination plants are emerging and should provide the next technological jump.
It is still expensive water, however, and requires avid attention to the quality of the network into which it is introduced. Expensive desalinated water will be a meager solution for cities with networks that lose more than one third of the water that is pumped into them -- as common occurrence in many developing countries,.