<p>Pathogens transmitted via the faecal-oral route remain a&#xa0;major public health risk, particularly when surface waters are used as raw water resources for drinking water production. Traditionally, regulatory monitoring has primarily focused on compliance with indicator-based limit values. However, the current World Health Organization (WHO) Guidelines for Drinking-water Quality, the new EU Drinking Water Directive, and its implementation in the Austrian Drinking Water Ordinance require a&#xa0;preventive, health risk-based approach along the entire supply chain—“from the catchment to the consumer”. This article presents an integrated modelling framework that operationalizes these requirements at the catchment scale.</p><p>Scientific advances over the past two decades—most notably the development of quantitative microbial risk assessment (QMRA) and the establishment of molecular DNA/RNA-based diagnostics for microbial source tracking (MST)—now enable health-based risk assessments that were not feasible under earlier regulatory paradigms. The presented approach integrates these methodological components with hydrological catchment modelling and pathogen fate and transport modelling within the QMRAcatch framework. Based on this integration, log₁₀ pathogen reduction targets can be derived from health outcome targets, here defined as a&#xa0;maximum acceptable infection risk of 1&#xa0;case per 10,000 persons per year.</p><p>The River Danube at Vienna, a&#xa0;large wastewater-impacted river relevant for drinking water supply, serves as case study. Scenario simulations assess the effects of climate change, population growth, and wastewater management measures anticipated under the new EU Urban Wastewater Directive on viral, bacterial and protozoan pathogens of faecal origin and required log₁₀ pathogen reduction targets. Results indicate that improvements in wastewater treatment—particularly advanced treatment stages and the reduction of combined sewer overflows—have a&#xa0;substantially greater impact on microbiological water safety than climate or demographic changes alone. The study demonstrates how site-specific, system-wide log₁₀ pathogen reduction targets can be derived as the sum of natural barriers and technical treatment steps, and how integrated catchment-based modelling supports the further development of water safety planning within a&#xa0;preventive, risk-based drinking water management framework.</p><p>This article is based on Demeter, Derx et&#xa0;al., Modelling the interplay of future changes and wastewater management measures on the microbiological river water quality considering safe drinking water production (<CitationRef CitationID="CR11">2021</CitationRef>) Science of the Total Environment Volume 768, Art. Nr. 144278. The original publication was condensed, and a&#xa0;discussion of the requirements of the EU Drinking Water Directive was added. This study forms part of the scientific collaboration <i>Vienna Water Resource Systems 2020+</i> and was presented at the Mid-Term Symposium 2025.</p>