In urban areas, water is utilized for different purposes and is often abstracted from the aquifer below the location where it is used. The density of sources of contaminants and the intensity of groundwater pollution in these areas are extremely high. Substantial areas of the groundwater resource are contaminated to an extent which excludes direct use for drinking water and the preparation of food, according to quality standards laid down by the European Community. The control of water quality must be effective, and preventive and remedial actions will have to be initiated to improve the situation. High costs, the low awareness of the general public, and the low velocity of the groundwater are the main reasons why a general improvement of the situation will be difficult to achieve. The groundwater quality was investigated in the aquifer below the City of Hanover over a period of three years. It is evident that (a) the quality, (b) the composition, and (c) the sources of contaminants do not differ substantially from those aquifers below urban areas with a similar industrial, commercial and agricultural structure as the area under investigation.