The growing global sand crisis emphasises the urgent need to identify alternative sources of silica sand. Construction-grade sand, in particular, is the most extracted solid material worldwide after water, with annual consumption reaching record levels due to rapid urbanisation and infrastructure expansion. Sand extraction is directly linked to riverbed degradation, coastal erosion, and habitat destruction, leading to severe environmental damage. In accordance with circular economy objectives, valorising quartz-rich waste through industrial symbiosis reduces both disposal costs and the demand for virgin raw materials. In addition to these environmental and economic incentives, silica’s intrinsic properties also contribute to its value. In many industrial sectors, including composites and construction materials, silica (SiO₂) is valued for its mechanical strength, thermal stability, and chemical resistance. These characteristics allow it to act as a performance-enhancing material rather than a simple filler. This review presents a detailed examination of the evolving processes within wastewater treatment plants (WWTPs) that enable the recovery of silica sand in support of the circular economy. It systematically explores the origins and movement of silica sand within wastewater, the technologies used for its recovery and purification, characterisation techniques, applications in GRP pipe production, policy mechanisms that support circular flows, and areas for future research. By synthesising current scientific knowledge and presenting practical examples, this article aims to promote broader adoption of silica sand recovery and contribute to the creation of sustainable urban material systems.