Water is one of our basic natural resources, habitat for animals and plants and essential for human life – but human uses pollute it and disrupt the natural water cycle. The aim of precautionary water management is to strike a balance between the diverse interests of its users and to prevent overuse of this natural resource. Groundwater characteristics are influenced by many natural (geogenic) and anthropogenic factors. Along with the water quality, the conditions for plants and animals in and beside streams and rivers are determined by the composition of the groundwater, the riverbed and the flood plain.

Hannover’s public wastewater system consists of the city sewer network and its two large treatment plants in Herrenhausen and Gümmerwald. Along with wastewater disposal, extending and renovating the sewer network, measures for further wastewater purification, environmentally sound disposal of residues, ecologically responsible disposal of sewage sludge, rainwater infiltration and semi-natural landscaping of watercourses are assuming increased importance for the city wastewater services.