In broad zones of the earth water is an essential but scarce commodity. Particularly the people in poor countries, for example Ethiopia, frequently do not have adequate access to water. Even more seldom is hygienic, clean drinking water. The World Health Organisation (WHO) estimates that only 60% of the world’s population has a permanent supply of water.

Most of us take water for granted as a commodity that is in plentiful supply and available cheaply at all times and in high quality. The daily water consumption of an adult in Europe is about 145 litres per day, of which only about three litres is drunk or used for cooking. The considerable remainder of 142 litres of drinking water is thoughtlessly flushed through the toilet (approx. 46 l), or used for personal hygiene (approx. 53 l), household tasks, the car and the garden.