Algae-Bacteria Community Analysis for Drinking Water Taste and Odour Risk Management

Geosmin and 2-MIB are bacterial secondary metabolites that create an earthy-musty taste and odour (T&O) in drinking water. Both compounds exhibit low odour thresholds and are leading causes of customer complaints to water companies worldwide. Water companies must predict spikes in T&O concentrations early to intervene before these compounds reach the treatment works. Cyanobacteria are key producers of T&O in open waters yet influences of broader microbial and algal communities on cyanobacterial T&O events remain unclear. This study identified T&O risk indicator taxa using next-generation sequencing of bacterial (16S rRNA) and algal (rbcL) communities in three reservoirs in Wales, UK. Ordination analysis of these communities revealed clustering according to assigned T&O concentration levels, identifying T&O signature communities. Random Forest (RF) analyses accurately classified samples for high and low concentrations of geosmin and 2-MIB, demonstrating the biological consortium’s predictive power. Based on shared ecological traits of significant bacterial and algal taxa, we propose five categories corresponding to different magnitudes of taste and odour risk. Indicator taxa in T&O risk categories can then be used to predict T&O events, empowering Water companies first to optimise a treatment response, but importantly to determine triggers before an event to evidence preventative intervention management.