Drinking Water Biofilm Management and Monitoring

Biofilms within drinking water distribution systems can pose risks to consumers, especially when mobilised, as high concentrations of microorganisms and associated material can be released leading to degradation of water quality. Access and sampling of biofilms within drinking water pipelines can be difficult without disrupting supply in these extensive and buried systems. A novel biofilm monitoring device was developed to determine if biofilm formation rates can be used to assess microbiological water quality, track fouling rates and ultimately indicate distribution system performance. The device comprises a sample-line pipe with multiple, independent removable sections (allowing for biofilm sampling) that can be easily connected to sampling points in the distribution system. Biofilm is removed from the device and flow cytometry used to determine total and intact cell concentrations. The biomonitoring device was tested in a series of laboratory trials, to establish the impact of different flow rates and orientations on biofilm formation and to determine the optimum configuration that achieves accurate and repeatable results. Subsequently, these devices were installed in two operational systems, with different water qualities, and biofilms were sampled for two months to obtain biofilm growth rates. The results provide the first direct evidence of different biofilm formation rates in distribution systems with different water qualities. This evidence is now being used to investigate fouling rates via risk analysis and modelling. The use of the device has potential to improve understanding of biofilm behaviour and help inform biofilm and asset management to safeguard the quality of delivered drinking water.