Water scarcity, population growth, and climate change put immense pressure on global water resources, challenging human health, environmental sustainability, and economic development. DECIRE-WATER addresses these issues by demonstrating innovative, scalable, and circular water and wastewater management solutions at five sites in Europe and one in South Africa. The project will provide pioneering, affordable, and sustainable decentralised systems, designed to function independently or integrated with centralised infrastructure, predominantly based on Nature-Based Solutions (NBS) but also incorporating technical processes. By project completion, our solutions will reach TRL 7-8 and be tailored to diverse geographic, climatic, and socio-economic conditions. Advanced monitoring technologies and digital tools will be incorporated to demonstrate that DECIRE-WATER can achieve the required level of safety and reliability, which is critical for achieving regulatory approval, public acceptance, and eventual market adoption. We will engage stakeholders through co-design and co-creation, fostering acceptance and market uptake, while developing a decision framework to guide policymakers. Public-private partnerships will also be explored to test sustainable business models. Our long-term impact by 2035, is to operate the DECIRE-WATER systems which will collectively drive €60 million in revenues and create 200 jobs in the water sector. In addition, our solutions will collectively benefit 7% of the European population by reclaiming over 7.8 million m³ of water annually, with estimated energy savings amounting to 751,300 MWh/year. By aligning with EU priorities on climate resilience, water security, and sustainability, DECIRE-WATER is well-positioned to meet global water management challenges, ensuring long-term impact and success.