SafeCREW Policy Brief #3 Managing the transition from non-disinfected to disinfected drinking water supply systems

Based on SafeCREW’s main findings, this policy brief provides evidence-based guidance for transitioning to disinfected drinking water networks, supporting decision makers and utilities in managing DBPs in water treatment and distribution systems. Recommendations for disinfection If the water distribuon network is well-maintained, UV disinfecon is highly recommended. The selection of disinfectants depends on source water and network conditions. Sodium hypochlorite (NaOCl) or chlorine dioxide (ClO₂) are generally recommended, while chloramine may be preferred in certain cases. For ClO₂, on-site generation, cold storage, and frequent monitoring of chlorite and chlorate are required, avoiding long-term storage. For NaOCl, storage time and temperature must be optimized to prevent chlorate formation considering site-specific factors. Disinfectant dosing should be kept at the minimum required to maintain microbial water safety. Advanced monitoring and automated dosing systems help achieve precise control, reducing the formation of regulated disinfection by-products (DBPs). Water utilities should implement or optimize treatment technologies, such as coagulation/flocculation, ozonation, activated carbon, or selective membrane adsorption, to selectively remove natural organic matter (NOM) that serves as precursor for regulated DBPs. Water utilities should use predictive or metamodel-based systems to optimize disinfectant dosing and minimize DBPs.