Source water catchments underpin the reliability, affordability and quality of South East Queensland’s drinking water supply, yet their full economic contribution is often underestimated in planning and regulatory processes. Despite previous efforts to quantify individual benefits, there was no consolidated, decision‑ready assessment that captures the breadth of economic values supported by source water catchments. This project addresses that gap by applying a modified ecosystem services framework tailored to internal frameworks and investment planning, to enable the identification, categorisation and economic valuation of key benefit streams across individual catchments. The analysis reveals significant economic value associated with healthy, well‑managed catchments, spanning avoided treatment costs and health impacts, recreational use and broader societal benefits. These findings provide a robust evidence base to strengthen cost–benefit assessments, guide strategic investment in catchment management, and support clearer communication of catchment importance to internal decision‑makers and the State regulator. The work demonstrates how a structured economic valuation approach can help catchment managers more effectively prioritise interventions and secure funding for long‑term catchment health in a changing climate.