The article "Biofilm Formation in Water Distribution Systems" by Patrícia Erdei-Tombor, Gabriella Kiskó, and Andrea Taczman-Brückner reviews the process of biofilm formation in drinking water distribution systems (DWDSs), focusing on the associated bacteria, chlorine resistance, and predominant surface materials. Biofilms, which are biologically active matrices composed of microorganisms and their extracellular products, can significantly impact water quality and public health. The study highlights the importance of understanding biofilm formation to prevent the spread of waterborne diseases and ensure safe drinking water. Key points include: 1. **Biofilm Formation**: Biofilms form on pipe surfaces due to the availability of nutrients and the protective benefits of adhering to solid surfaces. The formation of a conditioning layer on the pipe surface enhances nutrient absorption and promotes biofilm development. 2. **Bacteria in DWDS Biofilms**: Commonly studied bacteria in biofilms include *Pseudomonas*, *Staphylococcus*, *Enterococcus*, and *Helicobacter pylori*. These bacteria can cause various health issues, including gastroenteritis, skin diseases, and chronic infections. 3. **Material Effects**: Different materials used in DWDSs, such as PVC, HDPE, stainless steel, and cast iron, have varying effects on biofilm formation. Plastic materials like PVC and HDPE are generally more effective in controlling biofilm formation compared to metal materials. 4. **Chlorine Resistance**: The emergence of chlorine-resistant bacteria (CRB) poses a significant challenge in DWDSs. CRB can survive and grow despite the presence of chlorine, leading to increased risks of waterborne diseases. The mechanisms of CRB resistance include increased efflux systems, self-repair mechanisms, and enhanced nutrient absorption. 5. **Control Strategies**: Effective control methods for biofilm formation include reducing nutrient content, implementing disinfection measures, and using appropriate pipeline materials. Chlorination is a common disinfection method, but its effectiveness is declining due to the increasing prevalence of CRB. The authors emphasize the need for continuous research to develop innovative strategies and approaches to prevent and control biofilm formation in DWDSs, including the development of biofilm-resistant materials and residue-free chemical treatments. Standardized test methods are also recommended to ensure reliable comparisons of results.The article "Biofilm Formation in Water Distribution Systems" by Patrícia Erdei-Tombor, Gabriella Kiskó, and Andrea Taczman-Brückner reviews the process of biofilm formation in drinking water distribution systems (DWDSs), focusing on the associated bacteria, chlorine resistance, and predominant surface materials. Biofilms, which are biologically active matrices composed of microorganisms and their extracellular products, can significantly impact water quality and public health. The study highlights the importance of understanding biofilm formation to prevent the spread of waterborne diseases and ensure safe drinking water. Key points include: 1. **Biofilm Formation**: Biofilms form on pipe surfaces due to the availability of nutrients and the protective benefits of adhering to solid surfaces. The formation of a conditioning layer on the pipe surface enhances nutrient absorption and promotes biofilm development. 2. **Bacteria in DWDS Biofilms**: Commonly studied bacteria in biofilms include *Pseudomonas*, *Staphylococcus*, *Enterococcus*, and *Helicobacter pylori*. These bacteria can cause various health issues, including gastroenteritis, skin diseases, and chronic infections. 3. **Material Effects**: Different materials used in DWDSs, such as PVC, HDPE, stainless steel, and cast iron, have varying effects on biofilm formation. Plastic materials like PVC and HDPE are generally more effective in controlling biofilm formation compared to metal materials. 4. **Chlorine Resistance**: The emergence of chlorine-resistant bacteria (CRB) poses a significant challenge in DWDSs. CRB can survive and grow despite the presence of chlorine, leading to increased risks of waterborne diseases. The mechanisms of CRB resistance include increased efflux systems, self-repair mechanisms, and enhanced nutrient absorption. 5. **Control Strategies**: Effective control methods for biofilm formation include reducing nutrient content, implementing disinfection measures, and using appropriate pipeline materials. Chlorination is a common disinfection method, but its effectiveness is declining due to the increasing prevalence of CRB. The authors emphasize the need for continuous research to develop innovative strategies and approaches to prevent and control biofilm formation in DWDSs, including the development of biofilm-resistant materials and residue-free chemical treatments. Standardized test methods are also recommended to ensure reliable comparisons of results.