No abstract

Bacteriological failure investigations are crucial in the provision of safe, clean drinking water as part of a process of quality assurance and continual improvement. However, the financial implications of investigating coliform and Escherichia coli failures during routine water quality monitoring are poorly understood in the industry. The investigations for 737 coliform and E. coli failures across five UK water companies were analysed in this paper. The principal components of investigation costs were staff hours worked, re-samples collected, transportation, and special investigatory activities related to the sample collection location. The average investigation costs ranged from £575 for a customer tap failure to £4,775 for a water treatment works finished water failure. These costs were compared to predictions for US utilities under the Revised Total Coliform Rule. Improved understanding of the financial and staffing implications of investigating bacteriological failures can be used to budget operational expenditures and justify increased funding for preventive strategies.

ABSTRACTGlycogen is accumulated during the latter half of the diel cycle inSynechococcussp. strain WH8103 following a midday maximum inglgA(encoding glycogen synthase) mRNA abundance. This temporal pattern is quite distinct from that ofProchlorococcusand may highlight divergent regulatory control of carbon/nitrogen metabolism in these closely related picocyanobacteria.

A meta-analysis of existing available Illumina 16S rRNA datasets from drinking water source, treatment and DWDS were collated to compare changes in abundance and diversity throughout. Samples from bulk water and biofilm were used to assess principles governing microbial community assembly and the value of amplicon sequencing to water utilities. Individual phyla relationships were explored to identify competitive or synergistic factors governing DWDS microbiomes. The relative importance of stochasticity in the assembly of the DWDS microbiome was considered to identify the significance of source and treatment in determining communities in DWDS. Treatment of water significantly reduces overall species abundance and richness, with chlorination of water providing the most impact to individual taxa relationships. The assembly of microbial communities in the bulk water of the source, primary treatment process, and DWDS is governed by more stochastic processes, as is the DWDS biofilm. DWDS biofilm is significantly different to bulk water in terms of local contribution to beta diversity and in types of taxa present. Water immediately post chlorination has a more deterministic microbial assembly, highlighting the significance of this process in changing the microbiome although elevated levels of stochasticity in DWDS samples suggest that this may not be the case at customer taps. 16S rRNA sequencing is becoming more routine and may have several uses for water utilities including detection and risk assessment of emerging pathogens like Legionella, Bacteroides and Mycobacterium; assessing the risk of nitrification of DWDS; improved indicators of process performance and monitoring for significant changes in the microbial community to detect contamination. Combining this with other quantitative methods like flow cytometry will allow a greater depth of understanding of the DWDS microbiome.