Investigating the influence of tank material and residual chlorine on the proliferation of bacterial biofilm growth in the drinking water storage systems

ABSTRACT Biofilms are the primary reservoirs for microbial communities established in drinking water distribution systems and they exert considerable influence on the overall safety and quality of potable water. The current study centered on investigating the development of biofilms within water storage tanks of the National University of Islamabad, Pakistan. Two types of tank materials, polyvinyl chloride (PVC) and reinforced cement concrete (RCC), were selected to study the impact of the material and residual chlorine on biofilm formation, over 15 and 30 days. The findings revealed that water samples showed a high degree of bacterial contamination, with biofilm formation on both PVC and RCC surfaces, attributed to low residual chlorine levels. Bacterial quantity and diversity through heterotrophic plate count and images obtained from scanning electron microscopy showed that RCC surfaces promote denser biofilm growth owing to their roughness, underscoring the varied growth potential of different tank materials. Elemental analysis using energy dispersive x-ray spectroscopy revealed increased carbon content in biofilms, suggesting the role of organic compounds in microbial nourishment. The present study highlights the significance of selecting appropriate material for water distribution, which affects bacterial growth and proliferation. Besides, it emphasizes the need to maintain adequate residual chlorine levels to inhibit biofilm formation.