The eco machine that can magic water out of thin air

• Ed Pilkington in New York
• guardian.co.uk, Sunday November 23 2008 00.01 GMT
• The Observer, Sunday November 23 2008
• Article history

Water, Water, everywhere; nor any drop to drink. The plight of the Ancient Mariner is about to be alleviated thanks to a firm of eco-inventors from Canada who claim to have found the solution to the world's worsening water shortages by drawing the liquid of life from an unlimited and untapped source - the air.

The company, Element Four, has developed a machine that it hopes will become the first mainstream household appliance to have been invented since the microwave. Their creation, the WaterMill, uses the electricity of about three light bulbs to condense moisture from the air and purify it into clean drinking water.

The machine went on display this weekend in the Flatiron district of Manhattan, hosted by Wired magazine at its annual showcase of the latest gizmos its editors believe could change the world. From the outside, the mill looks like a giant golf ball that has been chopped in half: it is about 3ft in diameter, made of white plastic, and is attached to the wall.

It works by drawing air through filters to remove dust and particles, then cooling it to just below the temperature at which dew forms. The condensed water is passed through a self-sterilising chamber that uses microbe-busting UV light to eradicate any possibility of Legionnaires' disease or other infections. Finally, it is filtered and passed through a pipe to the owner's fridge or kitchen tap.

The obvious question to the proposition that household water demands can be met by drawing it from the air is: are you crazy? To which the machine's inventor and Element Four's founder, Jonathan Ritchey, replies: 'Just wait and see. The demand for water is off the chart. People are looking for freedom from water distribution systems that are shaky and increasingly unreliable.'

For the environmentally conscious consumer, the WaterMill has an obvious appeal. Bottled water is an ecological catastrophe. In the US alone, about 30bn litres of bottled water is consumed every year at a cost of about $11bn (£7.4bn).

According to the Earth Policy Institute, about 1.5m barrels of oil - enough to power 100,000 cars for a year - is used just to make the plastic. The process also uses twice as much water as fits inside the container, not to mention the 30m bottles that go into landfills every day in the US. But the mill also has downsides, not least its $1,200 cost when it goes on sale in America, the UK, Italy, Australia and Japan in the spring. In these credit crunch times that might dissuade many potential buyers, though Ritchey points out that at $0.3 per litre, it is much cheaper than bottled water and would pay for itself in a couple of years.

There is also the awkward fact that although there is eight times more atmospheric water than in all the rivers of the world combined, it is unevenly distributed. Those areas of the US that are most desperate for more water - such as the arid south-west where ground water levels are already dramatically depleted - have the lowest levels of moisture in the air.

The mill ceases to be effective below about 30 per cent relative humidity levels, which are common later in the day in states such as Arizona. To combat that problem, the machine has an intelligent computer built into it that increases its output at dawn when humidity is highest, and reduces it from mid-afternoon when a blazing sun dries the air.