A Dutch invention, the ‘WaterPyramid’, makes drinking water from sea water at an affordable price and is especially suited to developing countries. The secret – the use of free solar energy to purify the water…

The scarcity of water is a global problem, with many thousands of people dying because of sub-standard drinking water. The World Health Organisation estimates that each year over one and a half million children, most of them in the tropics, die as a result of the problem.

The solution may just lie in the water pyramid, a cheap water purification system invented by the engineer Martijn Nitzsche from Delft in the Netherlands. He has been awarded a World Bank prize for his work. He believes the root of the problem lies in the fact that 98 percent of the world’s water is saltwater in the sea. Freshwater accounts for just two percent, and half of that is permanently frozen in the form of polar ice.

“We’re all focussing on one percent of water, that small amount of freshwater, and we’re trying to purify that. This WaterPyramid takes saltwater to begin with and makes it into drinking water.”

The sun
The way the WaterPyramid works is amazingly simple: it is an enormous inflatable space, rather like inflatable tennis courts, but in the form of a pyramid and made from transparent plastic. It works as follows:

1. Sunlight penetrates the plastic, heating the interior to a temperature of around 70 degrees Celsius.
2. There is a shallow basin of un-purified saltwater on the floor of the pyramid. The water evaporates in the heat, and forms condensation droplets on the inside of the structure.
3. The droplets comprise distilled water, free of salt and bacteria. Perfect drinking water.
4. When they become heavy enough, the droplets run down the steeply inclined sides and are gathered in gutters which lead to an underground tank.

The figures
In the tropics an inflatable pyramid 30 metres wide can produce 1000 litres of pure drinking water each day, enough for 300 to 400 people. With the pyramid costing about 150,000 euros at current prices, and having an estimated life expectancy of close to a decade, the price of a litre of drinking water would be between one and two euro cents.

That seems cheap, but for people in developing countries it is still a problem. Mr Nitzsche touches a raw nerve:

“People there aren’t accustomed to paying for water. And, if you come up with a new system and say it’ll cost one or two euro cents, …well, people have to get used to the idea. You can have wonderfully clever technology, but it’s all actually about getting people aware of the facts - ‘Wow, I have no pain in my stomach any more, and I’ll live ten years longer!’ It’s still difficult to get people to take it in.”

The message does appear to be getting through. In Gambia and Senegal, two WaterPyramids are already in use. The local people, who also operate them, are very satisfied. In the near future, water pyramids are going to be set up in Indonesia which, with its thousands of small islands, is a perfect location. As the pyramids start being mass-produced, the price is expected to drop from the present 150,000 euros to 15,000 euros, nothing compared to the cost of traditional purification installations. NGOs are already showing great interest in the technology.
 

Click here for more information on the WaterPyramid.