Clever way to purify water – “Tanzanian villagers have begun using an energy-saving method to sterilise their drinking water – leaving the water under the sun. About 40 houses in Ndolela are using solar purification. Mrs Longwa says the process is simple to follow. “I fill the plastic bottles, put the lids on, then put them on my black-painted roof where they stay for a whole day.” The sun heats the water, helped by the black roof, which helps to absorb the heat. Solar radiation means a combination of ultra-violet rays and heat destroys the bacteria which cause common water-borne diseases like cholera, typhoid, dysentery and diarrhoea. After eight hours in the sun, it is ready to drink.” [via] – Link.