Statistical investigation of trends and spatial distribution of Danish drinking water quality

Chapter 3 The data 3.1 GEUS and Jupiter database The analysis is based on data from Jupiter, the national borehole database, maintained by GEUS (Geological Survey of Denmark and Greenland). The database contains data on wells, geology, water level and groundwater chemistry, as well as data about water supply, water abstraction licenses, yearly abstraction, and the exchange of drinking water between waterworks installations in addition to the chemistry of drinking water. Data are provided by the drilling companies and waterworks. Data are collected following a timetable depending on the annual discharge of treated or distributed water in accor- dance with Danish legislation (see Table 3.1). In the normal controls, the compounds analyzed are NVOC, ammonium, iron, manganese, chloride, uoride, nitrate, nitrite, sulfate, temperature and pH; in the extended controls TDS, calcium, magnesium and hydrogen carbonate are also analyzed. The choice analyze the data from the euent of the treatment plants was taken owing to the following reasons: To investigate the actual drinking water quality that one Danish citizen takes. In fact, one water work can be supplied by more wells, also located far away from the water distribution system. Thus, sometimes it can be dicult to establish where a certain user’s water is taken. However, every user can determine which water works the water is treated by just looking at the bill. The water quality should be steady over time after treatment, but no investigations have been led so far to check it. Sometimes the water quality is not so stable as it is supposed to be owing to several causes (such as the change of wells from which the water is taken, changes in water treatment operation, the introduction of new law requirements, etc.). 15