Water management for development of water quality in the Ruhr River basin.

On the Ruhr, a small river running through hilly country and with a mean flow of 76 m3/s, 27 water works use the method of artificial groundwater recharge to produce 350 million m3 of drinking water annually. On the basis of a special act, the Ruhr River Association is responsible for water quality and water quantity management in the Ruhr basin. The present 94 municipal sewage treatment plants ensure that the raw water is sufficiently good to be turned into drinking water. In the Ruhr's lower reaches, where dry weather results in a 20% share of the entire water flow being treated wastewater, comparatively high concentration of substances of domestic or industrial origin are likely, including substances which municipal wastewater treatment measures cannot entirely remove. These substances include ammonium, coliform bacteria or pathogens, boron and organic trace substances. Although water treatment measures have greatly contributed to the considerable improvement of the Ruhr's water quality in the last few decades, it is desirable to continue to aim at a high standard of drinking water production technologies since the Ruhr is a surface water body influenced by anthropogenic factors. However, in the case of substances infiltrating into drinking water, legislation is required if a reduction of pollution appears to be necessary.