General Water Quality in Vienna

Practically throughout the year, the Viennese population is supplied with spring water from the Northern Calcareous Alps. In managing the spring protection forests, special attention is paid to low-impact, natural methods. This means that the forest stock may not be modified to any larger extent, as forests can offer particular protection to spring zones only if anthropogenic intervention is kept at a minimum. This ensures that the humus and soil will remain healthy and able to filter and store rainwater efficiently. Due to the specific nature of the subsoil (craggy calcareous mountains), thawing periods and violent thunderstorms can trigger pollutant immissions from the surface. For this reason, a safety disinfection cycle is stipulated under law. In Vienna, this is done with chlorine and chlorine dioxide.

In periods of high water demand (for example during hot spells) or during maintenance or repair works of the Spring Water Main, additional water is fed into the network from the Lobau well-field. These wells are situated in the Danube Floodplains National Park. The water thus withdrawn is bank-filtered from the groundwater flow running parallel to the Danube. The advantage of this water resource lies in the high quality resulting from the good filtering (purification) effect of the soil.

Like spring water, groundwater, too, is disinfected using chlorine and chlorine dioxide.