Action needed to maintain drinking water quality

Gepubliceerd: 18 maart 2014

At all the locations in the Netherlands where surface water is abstracted, water quality is under pressure as a result of climate change. Action is needed to maintain the quality of the water for use as drinking water in the future. The most promising approach is a combination of policy measures, changes in the water system and more extensive treatment by the drinking water companies.

That is the outcome of a joint study conducted by Deltares, the KWR Watercycle Research Institute and the National Institute of Public Health and the Environment (RIVM). Water quality worsens when the amount of water flowing through the rivers declines during long periods of drought. Wastewater discharges have much more effect on water quality at these times because the concentrations of contaminants in the discharges are not diluted to the same extent.

In addition, drought can also result in water shortages in the Meuse and in the salinisation from the North Sea of the river water in the Lek. The water cannot be used as drinking water during these periods without putting extra measures in place.

A possible policy measure would therefore involve linking discharge permits to the amount of water flowing through the river. In practice, this means that many discharge permits would be stricter. Another measure would involve changes to the approval policy for various substances, and factoring in the effects of climate change on substance approval.

Meuse, Waal and Lek

A possible change to the water system could involve increasing the amount of water in the Meuse or the Lek rivers during dry periods by diverting water from the Waal river. This would dilute wastewater discharges into the Meuse and the Lek and could also help to counteract the salinisation of the Lek. A proposal has been made for the deployment of more, or different, types of plant for the purposes of more intensive treatment by the drinking water companies.

Changes to sewage treatment plants

An effective option for dealing with the contamination of surface water by medicines and other substances, particularly during low-water periods, could be more extensive treatment in sewage treatment plants. However, this treated water still contains traces of medicines because the treatment process at the plants does not target these substances.

In addition to drinking water abstraction, other forms of water use, such as recreation and nature, can also benefit from more extensive treatment at sewage water treatment plants. However, because of the costs involved, this study classified this measure as being less promising.

Drinking water in the future
The study was conducted for the Ministry of Infrastructure and the Environment with the aim of maintaining good drinking water supplies in the future. The Netherlands takes 40 per cent of its drinking water from surface water.

Click here for the full text of the report (Dutch).