Supporting the development of climate-resilient water safety plans through a risk-screening framework for drinking water source protection

Climate change-induced impacts on water-quality challenge risk management of drinking water. Uncertainty around future changes and limited resources require approaches that enable prioritisation at regional or national scale for planning and adaptive intervention. This paper presents a framework for risk screening drinking water supplies, providing a staged approach to building the capacity for integrating climate change into risk management. The framework is applied to drinking water sources of the Scottish national drinking water provider, developing raw water trajectories for indicative water-quality parameters (water colour and Escherichia coli). It establishes baseline understanding of water-quality controls through multivariate statistical analysis. It incorporates climate and land-use change into the model using climate (UKCP18) and land-use projections. The results suggest potential higher organic carbon production in soils from increased production with higher temperature, combined with reduced dilution and drought effects from reductions in summer rainfall. For E. coli, risks arise through land-use change leading to potential agricultural intensification. The framework supports the targeted development of climate-resilient Water Safety Plans, prioritising systems most at risk of raw water-quality deteriorations. It emphasises source protection to maintain or improve regulatory compliance, minimise socioeconomic and environmental harms, and generate additional benefits.