Bilge Vessel + Scupper Valve is a decentralized greywater collection, recycling system that bridges the gap between theoretical research and practical application. This system reduces the water demand, essential for sustainable development, by collecting, treating, and reusing greywater generated in a household at the source without requiring any modifications in the current home plumbing system. With this product-driven intervention, a family can save 5,000-6,000 litres of potable water/month and can reduce 50% of their water demand. This decentralised approach reduces carbon emissions by 80-85% compared to the centralised STP setups. It therefore addresses two challenges: water scarcity and operational carbon emissions linked to freshwater supply, treatment and conveyance of treated water, contributing to embodied carbon savings in plumbing infrastructure, STP construction.