Success factors for implementing decentralised urban water management solutions – a systematic comparison of lighthouse initiatives in the US, Europe and India

A key challenge in developing sustainable cities is establishing circular infrastructure systems. Decentralised urban water management solutions (DUWMS) are a case in point: Innovative DUWMS that allow recycling the water, heat, energy, or nutrients contained in wastewater locally are currently emerging in cities around the world. These systems could significantly enhance cities’ water resilience and sustainability. Yet, well-documented templates and best practices for implementation at scale remain scarce. Using a qualitative approach combining a literature review with 125 expert interviews, we systematically compared five DUWMS at building vs. neighbourhood scales and in high- vs. middle-income contexts. This structured cross-comparison distils six systemic factors enabling successful implementation and scaling.