Making drinking water out of sea water is a growing trend but a potential threat to the environment that could also exacerbate climate change, says WWF in a global review of desalination plants worldwide.

The WWF review, Making water: Desalination – option or distraction for a thirsty world?, shows that some of the driest and thirstiest places are turning to desalination. These include regions where water problems affect large, populous areas — Australia, the Middle East, Spain, the UK and US, with India and China following suit.

“Desalinating the sea is an expensive, energy-intensive and greenhouse gas emitting way to get water,” says Jamie Pittock, Director of WWF’s Global Freshwater Programme.

“It may have a place in the world's future freshwater supplies but regions still have cheaper, better and complementary ways to supply water that are less risky to the environment.”

It is estimated that around 60 per cent of freshwater needs in the Arabian Gulf are met through desalination, and the Australian city of Perth may be looking to source one-third of its freshwater the same way. Spain is devoting an astonishing proportion of its desalinated water to agriculture — at 22 per cent the highest level in the world – as well as to holiday resorts in arid areas.

Impacts of desalination include brine build-up, increased greenhouse gas emissions, destruction of prized coastal areas and reduced emphasis on conservation of rivers and wetlands. Many of the areas of most intensive desalination activity also have a history of damaging natural water resources, particularly groundwater.

Managing water demand and assessing impacts of any large-scale engineering solution are needed early in order to avert irreversible damage to nature and the cost overruns, often paid by citizens over the long haul. Sustainable sources of water start with protecting natural assets such as rivers, floodplains and wetlands. These natural systems purify and provide water as well as protect against extreme or catastrophic events.

“Large desalination plants might rapidly become ‘the new dams’ and obscure the importance of real conservation of rivers and wetlands,” adds Pittock.

“As with any relatively new engineering such as large dams that grew up in the 50s, the negatives become known when it is too late or too expensive to fix. What we need most is a new attitude to water not unchecked expansion of water engineering.”