Understanding the negative impacts of land use/land cover (LULC) on water quality is key to developing effective integrated catchment management strategies. However, in line with the Integrated Water Resources Management (IWRM) philosophy, this necessitates the generation and application of useful scientific knowledge, which stakeholders and policymakers can use to inform coordinated decision‐making processes. To facilitate this, a recently published study reported methods for estimating minimum thresholds of natural vegetation necessary for the maintenance and protection of water quality in South African catchments. The present article discusses the application and implications of these findings, focusing on the vulnerability of South Africa's Strategic Water Source Areas (SWSAs) to land‐use‐related water quality impacts. It emphasizes that, due to the significant land use transformations that have already occurred in these areas, and the consequent likelihood of water quality impairment, there is a need to restore and preserve sufficient areas of natural land cover to protect these strategic water resources from unacceptable levels of contamination.