Water Reuse and Closing the Water Cycle

The availability of sufficient and reliable freshwater is under pressure worldwide. Climate change, deteriorating water quality, land subsidence, population growth, and rising water demand present new challenges for water management. In this context, there is an urgent need to use water more efficiently and to close water cycles. 

Water reuse and water cycle closure are essential strategies that offer solutions to reduce the pressure on freshwater availability. By repurposing treated wastewater for agriculture, industry, or even drinking water production, dependency on natural sources can be reduced. KWR researches and develops strategies, technologies, and methods to implement these transitions in a robust, safe, and sustainable way. 

Projects such as Urban Waterbuffer, COASTAR and the Bedrijfsoverstijgende Water-Matchmaker contribute to a resilient and robust water supply, demonstrating how reuse and subsurface buffering can better align water demand and availability—even during times of scarcity.

Why close the Water Cycle?

The traditional linear water chain—from intake to discharge—is no longer sustainable. By closing waterloops at local or regional levels, we can ensure water availability where and when it is needed. This requires structural system-level changes as well as smart local decision-making. KWR supports this transition with knowledge on water quality,  soil,  purification, pipeline transport, system analysis, water demand and future scenario exploration.

Water Reuse: From Wastewater to Valuable Resource

Treated urban and industrial wastewater is increasingly seen as a reliable alternative freshwater source. KWR works on technologies and systems for safe and efficient purification, resource recovery, and water redistribution.

Examples of practical implementation include: 

• HomeWaterLab: A practice-based setup that allows for experimentation with decentralized treatment and reuse.

• Circular Living Labs and Alternative Water Sources. Use of rainwater and greywater at the household or district level for non-potable purposes, and treated effluent (from industrial process water or municipal wastewater) for central drinking water supply.

• Water Hub Eerbeek: Treatment of process water from paper and cardboard factories and recovery of by-products for reuse.

• Dairy Industry Water Reuse: Reuse of wastewater from dairy processing for agricultural and system-level applications.
• Closing the Water Cycle in North Holland: To fully close the cycle, effluent must undergo advanced treatment, including removal of organic micropollutants.

Benefits of Circular Water Projects

Circular water initiatives offer numerous ecological, economic, and societal benefits: 

• Improved Water Security: Local water reuse reduces reliance on external sources.

• Climate Adaptation: Cycle closure helps mitigate drought, heat, and stormwater challenges.

• Resource and Energy Recovery: Innovative techniques enable recovery of nutrients, heat, and other valuable substances from wastewater.

• Spatial Quality and Liveability: Smart water solutions contribute to greener, cooler, and healthier urban environments.

• Societal Engagement: Circular projects encourage cooperation among citizens, businesses, and governments. 

Water Quality and Public Health

Protecting public health is central to water reuse and cycle closure. KWR investigates how to effectively manage potential risks from pathogens and pollutants, using advanced purification technologies and monitoring. Developments like non-target screening and AquaPriori enable early detection of unknown substances and help predict their behavior in the water chain. Research also focuses on emerging pathogens, risk management strategies, and the effectiveness of treatment barriers. By combining this knowledge with risk assessment and governance, KWR supports the safe reuse of water in industry, agriculture, and indirectly in drinking water production.

Technology and Governance Go Hand in Hand

Technological innovation is essential but not sufficient on its own. Governance, organisation, and societal acceptance are equally critical. KWR explores how decision-making, regulation, and collaboration can support successful implementation of cycle closure. This includes approaches such as  Transformatief Omgevingsmanagement, which explores new forms of cooperation. In this way, we help water managers develop robust and adaptive strategies for a sustainable water cycle.

Legitimising Water Reuse and Social Integration 

The transition to a circular economy is generating promising technologies for the reuse of water and the recovery of nutrients and energy it contains. A key challenge is scaling up circular water solutions while ensuring social integration and legal compliance. How can such solutions be socio-technically legitimised through supportive regulation and institutional trust?

KWR investigates and identifies legitimisation strategies that can build institutional trust and foster societal integration of water reuse. One example is an exploratory study on public acceptance of water reuse. One example is an exploratory study on public acceptance of water reuse. In addition, the legal framework for water-related reuse has been mapped. Successful legitimisation strategies describe actions to enhance acceptance and adoption of water reuse—such as creating ambassadors within the water sector by sharing quality results from monitoring procedures and measurement systems. A synergistic approach, combining interconnected strategies, proves most effective.

Sustainability and Decision-Making

Water reuse and closing the water cycle demand sustainable choices that balance ecological, economic, and social dimensions. KWR develops knowledge and tools to support water managers in making such integrated decisions. This includes cost-benefit analyses, environmental impact assessments, and governance instruments to guide the design of circular water systems.

In research programmes like WiCE and projects like ANCHOR sustainability and reuse are linked to practical applications. KWR also develops methods for decision-making under deep uncertainty, such as (Dynamic Adaptive Policy Pathways), which allows exploration of flexible strategies to cope with future developments. This approach is crucial for infrastructure and technology investments in reuse, where uncertainty around climate, regulation, and human behaviour plays a major role. By connecting science, practice, and policy, KWR supports robust and future-proof choices for a sustainable water cycle. 

Want to Learn More About Water Reuse and Closing the Water Cycle

Water reuse offers multiple benefits. KWR investigates how this can be achieved safely, economically, environmentally, and socially—considering the entire water system. Follow our news page to stay informed on the latest insights, tools, and real-world examples.