Nowadays the problem of the water is becoming more important than ever before. After the World Water Day on 22th March 2007 many international organisations such as United Nations, WWF and others launched an alarm for the scarcity of water in the world and they made catastrophic predictions for the near future. In fact, many animal species are in danger of extinction and 1/3 of the global population risk to not have water in 2025. But the scarcity is not the only problem linked with water. There are also the pollution of water and the wrong use of it.