Water Reuse

Water Reuse, the use of reclaimed water from treated wastewater, has been a long-established reality in many (semi)arid countries and regions. It helps to alleviate water scarcity by supplementing limited freshwater resources.

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Water Reuse in the European Union

Water reuse enables circular water use, it fosters further elimination of pollutants and pathogens and can contribute to a reduction of freshwater usage and wastewater discharge. 

In Germany the recirculation of water is especially practiced in industrial sectors as e.g. paper production. Some EU member states, mostly in the Mediterranean, irrigate agricultural land with reclaimed water originating from urban wastewater. According to the European Commission’s „Blueprint to Safeguard Europe's Water Resources“ (2012) there is still significant potential to extend water reuse in response to climate change and water scarcity but a lack of common requirements prevents widespread uptake.

In response to that the European Circular Economy Action Plan defined actions to promote water reuse. This included “Guidelines on Integrating Water Reuse into Water Planning and Management in the context of the WFD” (published 2016) and a legislative proposal  on common minimum requirements for water reuse for agricultural irrigation and aquifer recharge (published 2018). On 26 June 2020 the new Regulation on minimum requirements for water reuse for agricultural irrigation entered into force and its provision will apply in all EU member states from 26 June 2023 onwards.

 

Agricultural irrigation demand in Germany

In principle, Germany is a country rich in water resources. We are only using 12.8 % of the 188 billion cubic metres of renewable water resources that are available. With 1.3 % of the total water abstractions (0.3 billion cubic metres) agricultural irrigation is comparable low in water demand (data from 2016). Due to climatic changes the agricultural irrigation demand can increase regionally and may exceed the natural groundwater recharge.

This can already be seen in some regions of Germany (see „Trockenheit in Deutschland – Fragen und Antworten“/ only in German).

Considering these developments, UBA has published a study on framework conditions for an environmentally friendly use of reclaimed water for agricultural irrigation (for an English summary see page 10 of the Study Report).

 

Risks for human health and the environment

Water reuse for agricultural irrigation poses potential risks for human health, soils and groundwater. In conventional wastewater treatment processes pathogens and pollutants are not fully eliminated. That long-term irrigation with conventionally treated wastewater may introduce micropollutants to the environment can be seen in the regions of Braunschweig and Wolfsburg. There, traces of pharmaceutical substances and x-ray contrast agents were detected in the groundwater (study results only in German). Advanced wastewater treatment and demand-based irrigation are crucial to limit the spread of pathogens, micropollutants (e.g. substances from pharmaceuticals, pesticides) and microplastic. Soil properties, hydrogeology, farming and irrigation practices further influence the potential risks for humans and the environment. Pathogens and pollutants can also be spread in the process of irrigation (especially spray/ sprinkler irrigation) or may be passed to humans or animals with the irrigated crops.  

There is a growing number of studies on potential uses, risks and necessary quality requirements of water reuse, including projects funded by the Federal Ministry of Education and Research. The recent funding measure “Future-oriented Technologies and Concepts to Increase Water Availability by Water Reuse and Desalination – WavE” included three projects related to the use of reclaimed urban wastewater (TrinkWave MULTI-ReUse and HypoWave). UBA was involved in TrinkWave. The WavE funding measure is now followed by the new funding measure „Wassertechnologien: Wiederverwendung“ (Water Technologies: Water Reuse”), in which UBA participates with the project PU2R „Point-of-Use Re-Use: Dezentrale landwirtschaftliche Wiederverwendung von häuslichem Abwasser zur Verringerung von Nutzungskonkurrenzen“ (Decentralized agricultural reuse of municipal wastewater to reduce competition for water) and „FITWAS - Wiederverwendung von Filterspülwässern aus der Grundwasseraufbereitung zur Sicherung der Trinkwasserversorgung“ (Reusing rinsing water from groundwater reclamation to secure drinking water supply).

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