Scientists at Stellenbosch University have developed a curious new way to purify small quantities of water - a nanotech teabag which fits onto the neck of a specially designed water bottle. The bag contains nano-scale microfibres that filter out microbes and other contaminants, as well as activated carbon which kills bacteria. One sachet cleans a litre of water to the same purity as bottled water, and the used sachet can be chucked into the nearest ditch after use, as it is completely biodegradable. The best thing about this new technology is that it inexpensive material are used to make the teabag water purifier. A single bag is estimated to cost less than 10 cents. Read more: SmartPlanet and PhysOrg.