From raw water to drinking water
In the case of water supply systems, the Drinking Water Ordinance distinguishes between the following:
Central waterworks with a daily supply of more than 10 cubic meters
Small waterworks that deliver less than 10 cubic meters of drinking water per day
Water companies extract the water from natural reservoirs, process it further and take over the distribution. The removal of the water takes place from groundwater, spring water or bank water pre-purified river water. Groundwater recharge increases the amount of water purified by natural barriers. The water extracted from natural resources and pre-purified by a large number of barriers is referred to as raw water in the regulation. Only when the quality of the raw water is high can it be directly distributed as drinking water without further treatment. If the raw water exceeds specified limits in the Drinking Water Ordinance, before being distributed to households and businesses, further purification of the water extracted from natural resources takes place in a water treatment plant. For processing, several process steps are used. In addition to mechanical processes, aeration, precipitation, filtration, flocculation and softening are often used processes to produce drinking water quality.