Although water is the most common substance on Earth, we should use it carefully because only 1% is drinkable and 1/3 of all the people in the world can't get enough clean water. Today, we use 3 times more water than in 1950, and people in rich countries use 10 times more than those in poor ones. So where does it all go? Well, a single dripping tap can waste up to 7,600 litres of water in a year and a leaking toilet can waste about 260 litres in a day.