Toilets as Climate Tools: How Resource-Oriented Sanitation Could Reshape Food Systems and the SDGs

Every flush carries more than waste. Human excreta contain the very nutrients that agriculture spends billions of dollars replacing with synthetic fertilizers, along with water and energy that conventional treatment plants simply discard. A new study published in Environmental and Sustainability Indicators argues that this overlooked stream could become one of the most powerful cross-sectoral levers for achieving the United Nations Sustainable Development Goals, with effects rippling far beyond the bathroom and deep into the world’s food systems. The research, led by Tamara Vobruba of BOKU University and colleagues, provides the first systematic assessment of how resource-oriented sanitation, or ROS, interacts with individual SDG targets rather than entire goals.

Resource-oriented sanitation represents a fundamental departure from the linear model that has dominated sanitation engineering for more than a century. Instead of collecting wastewater in energy-intensive networks and transporting it over long distances to centralized plants, ROS seeks to recover water, nutrients, organic matter and energy at or near the source. Technologies range from source separation of urine and faeces to treatment wetlands, struvite precipitation, alkaline urine dehydration and anaerobic digestion for biogas production. The approach treats wastewater not as a disposal problem but as a circulating resource stream, one that can simultaneously reduce pollution, ease pressure on freshwater supplies and return plant-essential nutrients such as nitrogen and phosphorus to agricultural soils.

The timing of the analysis is significant. Urbanization, population growth and climate change are intensifying competition for water, energy and food resources, a tension captured by the water-energy-food-environment nexus framework. Within this nexus, decisions in one sector cascade through the others: irrigation choices affect energy demand, fertilizer production drives greenhouse gas emissions, and wastewater discharge degrades the ecosystems that underpin food production. The United Nations’ 2030 Agenda, with its 17 goals and 169 targets, was designed to reflect these interdependencies, yet most sustainability assessments still operate at the coarse level of entire goals, obscuring the concrete interactions that policymakers actually regulate.

To close this gap, the research team applied a structured scoring method originally developed by Nilsson and colleagues in 2016 and adapted within Austria’s UniNEtZ project, a collaborative initiative of Austrian universities aimed at translating the SDGs into actionable national policy. Under the seven-point Nilsson scale, interactions range from +3, meaning an intervention is indispensable for achieving a target, down to -3, meaning it makes achievement impossible. Groups of at least three senior experts per SDG scored each interaction independently, provided written justifications, and then resolved divergences through moderated consensus deliberation. Simple averaging was prohibited, ensuring that disagreements were argued through rather than diluted numerically.

The results are striking. Of the 123 SDG targets assessed beyond SDG 6, 41 showed non-neutral interactions with resource-oriented sanitation, and every single one was positive. Four targets earned the highest score of +3, marking ROS as indispensable: sustainable and resilient food production under SDG 2.4, improved water quality and wastewater treatment under SDG 6.3, resource efficiency and decoupling growth from environmental harm under SDG 8.4, and upgrading infrastructure and industries for sustainability under SDG 9.4. A further cluster of reinforcing interactions, scored +2, spanned agricultural productivity, communicable disease prevention, sustainability education, water-use efficiency, renewable energy, green jobs, industrial innovation, urban sustainability, climate resilience and marine ecosystem protection.

The food-system lens reveals why these connections run so deep. Food systems are not merely agricultural production; they encompass processing, distribution, consumption and waste, embedded within social, economic, health and governance dimensions. When sanitation is reframed as part of the food system, the circularity becomes tangible. One illustrative calculation cited in the study found that wastewater from just 4 percent of Vienna’s population could supply the nutrients needed for the city’s vegetable production, equivalent to roughly one-third of local vegetable consumption. Closing that loop reduces dependence on synthetic fertilizers, whose manufacture is energy-intensive and emissions-heavy, while building soil health and buffering farms against price shocks and supply disruptions.

Water is the other critical thread. In Austria, irrigation water demand is projected to rise by around 80 percent by 2050, placing mounting pressure on groundwater resources that also supply drinking water. Reclaimed wastewater can substitute freshwater for irrigation and fertigation, directly improving water-use efficiency and relieving stressed aquifers. Source separation adds a further layer of protection: by isolating nutrient-rich and contaminant-rich streams before they mix, ROS reduces the release of pharmaceuticals and micropollutants into rivers, limits combined sewer overflows, and ultimately cuts the land-based nutrient runoff that drives eutrophication and ocean acidification in downstream marine environments, including the Danube-Black Sea corridor.

The study’s Austrian setting is itself noteworthy. Research on resource-oriented sanitation has concentrated overwhelmingly on low- and middle-income countries, leaving high-income, infrastructure-rich contexts underexplored. Austria is an instructive case: it enjoys excellent conventional sanitation, yet the European Union’s Water Reuse Regulation of 2020 established minimum quality requirements for agricultural water reuse that Austria opted not to implement, citing liability concerns and potential costs for farmers while acknowledging the need for re-evaluation. The new target-level evidence base is intended precisely to inform such reassessments, showing how even mature sanitation systems hold untapped potential for circular resource management aligned with broader sustainability objectives.

The authors are careful to delineate what the assessment does and does not show. The absence of negative scores does not mean trade-offs are impossible in practice; rather, it reflects that ROS, defined explicitly as promoting the safe reuse of water, nutrients, energy and materials in compliance with treatment standards, was judged not to systematically impede any SDG target in the Austrian context. Implementation barriers remain real and are not captured by the scoring framework: highly centralized infrastructure may limit the cost-effectiveness of decentralized solutions, regulatory uncertainty persists around recovered products, public acceptance hinges on risk perceptions, and low water tariffs and cheap synthetic fertilizers weaken the economic case. Emerging contaminants such as PFAS and microplastics add further technical and regulatory complexity to the safe reuse of recovered resources.

What emerges overall is a portrait of sanitation as a cross-sectoral enabler rather than a stand-alone service. The interaction patterns map onto every dimension of sustainable food systems: environmental benefits through pollution reduction and ecosystem protection, economic gains through reduced input dependency and new circular-economy jobs, social benefits through more equitable access to locally recovered resources, health gains through reduced pathogen exposure, and institutional benefits through the participatory governance that safe reuse demands. The UN-Water SDG 6 Synthesis Report 2026 identifies fragmentation between sectors as a key barrier to SDG progress, and this study offers a concrete methodological answer: by making target-level interactions explicit, expert-based assessments can give policymakers a structured, evidence-grounded basis for coordinating agriculture, energy, health, climate and water policy. If the toilet is to become a tool of the circular economy, the evidence now suggests the connections it forges may be among the most consequential in the entire 2030 Agenda.

Subject of Research: Target-level assessment of resource-oriented sanitation linkages with the Sustainable Development Goals in sustainable food systems

Article Title: Resource-oriented sanitation in sustainable food systems: Identification and analysis of linkages across the sustainable development goals

Article References: Vobruba, T., Delgado, C., Germann, V., Costa-Pereira, I., Wirth, M., Hartl, M., Huber-Humer, M., & Langergraber, G. (2026). Resource-oriented sanitation in sustainable food systems: Identification and analysis of linkages across the sustainable development goals. Environmental and Sustainability Indicators, 32, Article 101517. https://doi.org/10.1016/j.indic.2026.101517

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101517

Keywords: resource-oriented sanitation, sustainable development goals, food systems, wastewater reuse, nutrient recovery, water-energy-food nexus, circular economy, SDG interactions, Austria, sustainable agriculture, water reuse regulation, climate resilience