March 22nd is World Water Day

The UN designates March 22nd as World Water Day, to draw attention to the world supplies and uses of fresh water. It supports the management of fresh water supplies in a sustainable way, covering such issues as its scarcity, pollution, and access to it.

The UN will doubtless use the day to pass resolutions asserting everyone's 'right' to clean, fresh water, and demanding access to it for women, minorities, children and disabled people. It will issue school packs to make children aware of the importance of water, and organize competitions to have children draw pictures that illustrate it.

None of this will actually produce any more fresh water, but fortunately there are other people out there already doing just that. This is important. The pumping, treating and transporting of water uses about 8% of all energy generated. Sometimes its conservation can be achieved using natural means such as restoring or developing wetlands, or managing floodplains. The reintroduction of beavers into the UK is helping with that conservation.

Ultimately, however, and given the increasing demand for fresh water, the solution lies with developing new sources and new technology. Voluntary groups are assisting villagers to dig deep wells. Others are demonstrating how plastic bottles and sunlight can purify contaminated water. For an adequate supply of drinkable quality water, though, the future will have to involve the large-scale desalination of seawater.

A key problem is that the two main types of desalination, thermal and osmotic, are both energy intensive and expensive. But breakthroughs promise to reduce the costs. Israel has just upped the output of its Sorek plant, the world's largest reverse osmosis desalination plant. Built by Israel Desalination Enterprises, it produces enough fresh water to cover 20% of the country's households. Additional desalination plants are ramping up to produce 50% of the country's water needs. Its secret is good engineering. Is uses 16-inch pressure tubes instead of the usual 8-inch ones, meaning it needs only a quarter of the piping. It also uses highly efficient pumps and has energy recovery mechanisms, giving it the cheapest desalinated seawater in the world.

Another breakthrough has come in grapheme-oxide membranes. A University of Manchester group has announced in the journal Nature Nanotechnology that it can now prevent the membranes becoming swollen in water, and can precisely control their pore size, enabling unwanted salts to be sieved out at speed, leaving clean, drinkable water. They aim to scale this up into large-scale and cost effective plants.

By all means let us celebrate World Water Day. But let us remember as we do so that it is voluntary workers who are currently helping remote communities gain access to clean water, and it is engineers and entrepreneurs who are applying the work of researchers to give the world all the clean water it will need in the future. The doomsayers are wrong yet again. There will be no "water wars," largely because we are unlikely to run out of seawater or, indeed, of the human ingenuity that can process it.