Spatial risk assessment of drinking water contamination by nitrates from agricultural areas in the Silesia province

The main purpose of presented study was to show the potential threat of the access to drinking water of uncertain quality. Protection against contamination of natural aquatic ecosystems is the main action taken to reduce the danger of different threats. The European Union using legislation, through issuing the Water Framework Directive, established a plan in the field of water policy, aiming at protecting groundwater better. The Directive orders each Member State to use water in a rational way and obliges them to protect the water resources in accordance with the principles of sustainable development. The target of this paper is to analyze the variability of nitrates concentration in water intended for Silesian inhabitants consumption in the period of 2008-2012. In research methodology, water supply systems were divided into categories, depending on the daily demand of water or alternatively on the number of settlement units supplied with water. This variable was connected with the amount of quality water control and the probability of exceeding the maximum permissible concentration of nitrates in drinking water. The areas with the highest risk of nitrates contamination in a tap water were defined using the land cover layer and nitrates concentration in surface raw water and drinking water.