Transitioning surface water collection to surface water reuse systems: main report

Executive Summary

The Centre of Expertise for Waters (CREW) commissioned this capacity building project to help support Scottish Water’s ambition to reduce the volumes of rainwater entering the combined sewer network by transitioning Scotland’s surface water collection and treatment systems to surface water providing systems, enabling water reuse in the urban environment. This is driven partly by Scottish Water’s Climate Change Adaptation Plan 2024 (Scottish Water 2024) that describes how warmer and drier summers may increase the risk of deteriorating raw water quality, droughts and water security issues, and how more frequent, more extreme storms may disrupt Scottish Water assets and service provision. The Surface Water Policy (Scottish Water 2017) drives a “no more in, what’s in out” ambition to reduce the volume of rainwater entering the combined sewer system. One option to support this strategy is through the collection and reuse of rainwater for non-potable water use, such as for non-crop irrigation, green space cultivation, municipal cleaning activities, vehicle washing and industrial cooling applications. This proactive approach can help reduce sewer flooding and overflows into the water environment, while reducing overall demand for potable water supplies by reusing collected surface waters for non-potable purposes, particularly during periods of water stress.

This report addresses some of the knowledge gaps around the overall potential of Scotland’s surface water management network to provide a viable water source for wider non-potable uses. In particular, it focuses on improving knowledge of current best practice in water reuse in UK and international contexts, exploring the potential for place-based solutions for reuse of untreated surface waters, understanding regulatory requirements and barriers, and the economic drivers to enable this transition, as well as consumer enthusiasm to adopt surface water reuse.