Effects of climate change on water quality (KLIWAQ)

Dam and withdrawal tower of a drinking water reservoir

The effects of climate change on the quality of raw water resources were investigated. In addition to the vulnerabilities of the various water resources, recommendations for action were identified.

Climate change is causing meteorological changes, such as increased dry spells, heavy rainfall events, and temperature increases. These changes can affect not only the available water quantity but also the microbiological and physico-chemical quality of raw water resources. Within the KLIWAQ project, these effects of climate change on raw water quality were investigated based on a literature review, a survey of water supply companies with around 180 participants and a workshop. Recommendations for action were derived from the findings.

The survey and the workshop showed that the effects of climate change have so far mainly affected surface water resources, but also bank filtrate. Groundwater resources are currently less affected, as they show longer reaction times and the influence is more indirect.

Regardless of the type of raw water, temperature changes were by far the most frequently observed effect occurring today. However, the literature review showed that numerous other effects can also occur (e.g. a changing spectrum of organic trace substances, increased nutrient inputs, increased occurrence of coliform bacteria and algae blooms).

The results show that the available treatment technologies are generally sufficient to cope with the effects. It is therefore advisable for water supply companies to observe the effects through regular monitoring and to adapt the treatment if necessary. In summary, it can be stated that the effects of climate change on water quality in Germany are much less significant than the problems associated with limited water availability.