Recycling treated wastewater for irrigating green spaces

Brief intro to the WaterMan pilot measure

In the City of Kalmar in south-eastern Sweden, treated wastewater effluent originating from a municipal wastewater treatment plant is disinfected by further filtration and UV light treatment and then used to water green spaces. The process: treated wastewater is pumped from the wastewater treatment plant’s discharge channel into a mobile container. There, filtration and UV light are used to reduce the content of microorganisms. A mobile tanker then transports the water to the green areas, which are irrigated directly from the tanker using a hose system.

In terms of water quality, the treated and UV-disinfected water has the potential to meet the criteria for Water Class A under EU Regulation 2020/741, which would allow its use for irrigating edible crops in agriculture. While such a high standard is not technically required for watering urban green spaces, it provides a clear benefit: it helps build trust and acceptance among the operational staff and the wider public.

The system developed in Kalmar is not only functional – it is also replicable. It can now be purchased as a turnkey solution directly from the supplier, making it easier for other municipalities or water companies to adopt similar approaches.

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"Let it flow" - read the full story behind the pilot measure

After several droughts, it became clear that the municipality of Kalmar in Sweden urgently needed a new water strategy. The other important conclusion was that in order to develop it quickly, everyone should just get down to work and test out alternatives. Here is a report from a place where there is a lot going on and everything is flowing in the right direction. Read more...

In-depth information on the pilot measure

Pilot measure overview (final status) These slides present the final shape of the pilot measure, including its context, implementation, and key lessons learned.

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The evolution of the concept (from 2023 to 2025) These slides give an account of the work process behind the chosen technical-organisational concept, incl. considerations, recommendations and decisions taken at different stages. Scroll through the slides to chronologically follow the iterative “development journey” of the pilot measure step-by-step, from the initial idea to its present status!

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Collection of further materials

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