Water is vital to life The American Museum of Natural History has an exhibition on Water ( Water : H2O = Life.)
The exhibition shows the difference in usage in different parts of the world. The average North American, uses between 227 and 340 litres of water per day. Yet Atlanta, Georgia, will run out of drinking water within the next four months if it doesn’t rain soon. The city is experiencing its driest year since 1931. In some parts of sub-Saharan Africa, women spend between 15 and 17 hours a week collecting water..
20 litres per day is the minimum amount of clean water required to meet basic human needs, drinking, cooking and hygiene. Some people in parched places have to survive on just 5 litres or less. One quarter of Mexico City’s residents have no access to tap water; others have only 1 hour a week.
The exhibit’s emphasis is on water conservation. It takes 3 litres of water to produce a 1-litre bottle of bottled water .
There are innovative methods to extract, conserve and purify water. More than 700 PlayPump water systems have been installed in rural South Africa and other sub-Saharan countries. Children spinning on these colourful merry-go-rounds 16 times per minute generate enough energy to pump about 1,400 litres of water per hour from boreholes 40 metres deep. Perth , Australia gets 20% of its water supply from the Indian Ocean, desalinated with wind power. Windhoek in Namibia reclaims up to 30% of its water from sewage.
Bangladeshi women have cut cholera incidence in half using sari fabric, folded eight times, to filter bacteria from water.
Following the writings of Snow and the demonstration in the late 19th century that faecal contaminated water was a factor in the spread of cholera the London Corporation built separate water mains and sewerage tunnels emptying downstream into the Thames river, a system that is still in use. The Thames and Lee rivers now supply drinking water to 8.3 million residents in th London area every day.
Systems age and the antiquated system allows hundreds of millions of litres of untreated sewage to pass directly back into the rivers . This happens in London and in the River Forth in front of my house. .
Glausiusz J (2007) The liquid of life Nature vol 450 p 353

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