It was with great sadness that SIWI received news of the tragic passing of Arjen Hoekstra. His innovation of the water footprint has forever changed the way we understand the water impact of consumption and production.

The water community was shocked when it was known that one of its most influential members, Arjen Hoekstra, had passed away on 18 November. The water footprints Hoekstra invented in 2003, building on his mentor Tony Allan’s concept of virtual water, gave us a framework to analyze the link between human consumption and production and the appropriation of the globe’s freshwater. This innovation not only kicked off a whole new academic field, Water Footprint Assessment, but also made it possible for companies, governments and consumers to understand their water dependence in locations around the world and how their water footprint contributes to social, environmental and economic impacts in vulnerable river basins.

The water footprint is the actual volume of fresh water consumed or polluted by a process, a product or an organization. It can be used by consumers who want to eat or shop more sustainably, but also by companies to quantify their water consumption and pollution for their operations and supply chain, set targets for water footprint reduction and develop a corporate water sustainability strategy. Governments can use it to understand the water footprint of trade between countries. Thanks to Arjen Hoekstra, the international discussion about production and consumption and the trade of goods moved to a new level of clarity, making it much easier to go from intentions to action.

In 2008, Arjen founded the Water Footprint Network and together with Ruth Mathews, now at SIWI, her dedicated team and over 200 partners he created a vibrant global community of public, private, NGO and academic organizations that applied the latest research to reveal new ways to address critical sustainability challenges. The Water Footprint Network conducted a wide range of innovative projects across different scales, from global trade to smallholder farmers, building the evidence base for formulating policy, evaluating technologies and identifying best practices.

At the same time, as Professor of Water Management at the University of Twente in the Netherlands, Arjen Hoekstra worked tirelessly to expand the scientific understanding of the real appropriation of water required for different human activities.  He was one of the most cited researchers in his field, with publications on a broad range of water-related subjects, including food production, energy and trade. Among his books, which have been translated into several languages, can be mentioned The Water Footprint of Modern Consumer SocietyThe Water Footprint Assessment Manual and Globalization of Water. Over the years, many students have been a part of this endeavor, both at the University of Twente and elsewhere.

With the death of Arjen Hoekstra, the water world has lost one of its most brilliant and innovative minds. Furthermore, many of us have lost a friend, a colleague who inspired the best in us and a co-conspirator who challenged us to become better advocates for sustainable development. He often said his goal was to change the world. Arjen did more than his share of that.