Microbial dynamics at different stages of drinking water treatment systems

Abstract

As drinking water moves from its source through various treatment processes and distribution networks to the end users, its microbial communities are influenced by the effects of treatment processes, including source water type, treatment methods, and distribution system conditions. This review systematically explores the dynamic changes in microbial communities from the source to the tap and analyzes the key factors and positions that influence these changes. First, the roles of major treatment stages, such as coagulation–sedimentation, filtration, and disinfection, are reviewed, highlighting how these processes not only remove contaminants but also reshape the structure of microbial communities. Studies indicate significant differences between treatment stages in terms of pathogen removal and microbial community reconstruction. Ozone disinfection reduces microbial diversity and shifts community composition, often favoring ozone-resistant taxa such as Mycobacterium and Legionella. UV disinfection decreases overall microbial abundance and alters community structure, with a pronounced effect on Gram-negative bacteria and potential regrowth of UV-resistant species like Actinobacteria. The review then examines how physical, chemical, and biological factors impact microbial activity and microbial community composition, particularly in distribution systems with prolonged water retention times, where conditions may lead to microbial regrowth and biofilm formation. Additionally, advancements in modern technologies for monitoring microbial communities are discussed, which have greatly improved the ability to detect and characterize microbial dynamics. Finally, strategies for optimizing treatment processes and introducing innovative disinfection technologies to manage and control microbial communities in drinking water systems are proposed, ensuring the safety and stability of water supply systems.