Water for life

How can you sum up the importance of water to life on Earth? It covers 70% of the planet’s surface, makes up 50 to 70% of the human body, and adults need to drink around 2.5 litres every day. But still more than one billion people, mostly in developing countries, cannot access safe water for drinking, cooking, washing, growing crops or rearing livestock, according to UK charity Practical Action. Meanwhile one in eight people in the world drink water that contains pollutants, bacteria or viruses that are likely to make them ill, according to US-based group charity Water. So how can chemistry help to make water safe to drink, anywhere in the world?