A short abstract of the doctoral research

The drinking water sector faces increasing challenges due to climate change and human pollution. While high-quality water can be ensured at production, maintaining quality during distribution is more difficult. Drinking water distribution systems (DWDS) are complex environments where physical, chemical, and microbial processes interact, affecting water quality at the customer’s tap.

This dissertation investigated microbial dynamics in DWDS and the influence of external and operational factors. Using both lab-scale setups and a pilot-scale DWDS, we demonstrated that systems with mature biofilms were resilient to minor variations (e.g., pH) as well as environmental factors (e.g., temperature), and large-scale interventions (e.g., flushing procedures). Otherwise, the microbial quality of the bulk water phase was more dynamic over time and influenced by external factors such as water temperature and source water quality. Additionally, the role of biofilms in the transformation of odor precursors (halophenols) was evaluated, showing that mature biofilms and higher temperatures enhanced the formation of chloroanisoles. Furthermore, biostability was assessed in response to flushing (with and without chlorination) and the use of water with reduced organic carbon content. Both approaches resulted in a faster reduction of unwanted microorganisms, however, regrowth of the resident community was observed after flushing with chlorination. Finally, the insights gained from this research were combined and discussed within a broader and practical context.