The Flexitility research project entered its implementation phase in October 2022: by 2024, joint partners from practice and research will be testing possibilities for water reuse for agricultural irrigation and decentralized buffer storage of drinking water. The overriding question is how these concepts can serve to increase the flexibility and resilience of municipal and regional public services. To this end, pilot systems are being installed, test series with the systems are being carried out, the results are being evaluated and recommendations for action are being developed. In addition, a model for assessing municipal climate resilience is being launched for practical application.

Drinking water buffer storage to balance supply output

With the aim of smoothing out demand peaks in the drinking water network, a selection of largescale water consumers are being equipped with buffer storage systems for drinking water. The daily fluctuating demand for drinking water in the connected buildings is covered by the storage tanks, which are only filled with a low but continuous volume flow. Operational requirements, costs and benefits are determined in test series.

The effectiveness of the storage tanks in the context of the effects of extreme weather is scaled up and modeled for the entire drinking water network. A hydraulic model for the HWAZ supply network will be used to investigate the extent to which they help minimize pumping costs and network expansion costs. The hygienic and technical safety of the reservoir system will be ensured by intensive monitoring.

Testing of water reuse for agricultural and green space irrigation

For water reuse, treated water from the Uebigau wastewater treatment plant will be disinfected according to EU Regulation 2020/741 and used for irrigation of animal feed and energy crops. An agricultural area of 12ha in total is partly fully, partly deficiently and partly not irrigated at all for comparison purposes.

To assess risks for humans, animals and the environment, all relevant parameters in the irrigation water, in the soil, on the plants, in the groundwater and on the irrigated grassland are measured and analyzed. For this purpose, a risk management plan will be developed in close cooperation with the relevant authorities.

Assessment of municipal climate resilience

An indicator-based "climate resilience assessment tool" already outlined in the project will also be further developed and tested with municipal partners. It is designed to assess municipal utility infrastructures in terms of their resilience or ability to cope with extreme weather events.

In the end, operators should be able to draw on well-founded experience and proven business models and operating concepts to redesign supply infrastructures in a more climate-resilient and resource-conserving way with the help of water reuse and intermediate drinking water storage.