Very high standards are set for the quality of drinking water especially as regards chemical components and microbial composition because it is the foremost primary basic foodstuff for all kinds of civilization. It must be free of germs and chemical materials which can cause illness and should also be colourless, clear, cool, odorless and, last but not least, good to taste.
Water infrastructure systems are there to treat raw water and distribute good quality water to municipal and industrial areas. 95 percent of Germany’s drinking water comes from central water suppliers and 70 percent is recovered from surface water or bank filtration. Water is treated before consumption mainly to remove particles, iron and manganese but also to make it soft and free of germs.
Industrialized nations often waste good drinking water. In , approx. 120 liters of water are consumed per person and day. Public water infrastructure systems distribute nothing but drinking water although only about 2 liters of actual drinking water quality is really needed per person and day. Drinking water or water of a similar quality is used for cooking, making drinks, personal hygiene, cleaning dishes and washing clothes. However, large quantities are also used for tasks which could be carried out with water of a lesser quality viz. flushing toilets, cleaning buildings or watering gardens.
It would be relatively easy for each household to save water by installing appropriate taps and toilets. Vacuum and pressure systems are excellent alternatives to conventional gravity sewers. For example, flushing toilets could be replaced by vacuum toilets, already commonly in use on airplanes, ships and trains and even in some Scandinavian households. Decentralized or semi-decentralized wastewater purification systems also help save the costs which are currently incurred by maintenance work on central sewage systems.