# Divergent Bacterial Communities in Water and Sediment of Chlorinated Drinking Water Storage Tanks

## TL;DR

This study explores how bacterial communities in drinking water storage tanks differ between water and sediment, and how tank conditions affect water quality.

## Contribution

The study reveals distinct bacterial communities in water and sediment and identifies factors influencing their composition in chlorinated drinking water tanks.

## Key findings

- Water and sediment bacterial communities were dominated by Alphaproteobacteria and Gammaproteobacteria, respectively.
- Tank-specific characteristics and sediment accumulation influenced bacterial community composition.
- Genetic signatures of opportunistic pathogens were detected despite no presence of total coliforms or E. coli.

## Abstract

Properly operated
and maintained drinking water distribution
system
(DWDS) storage tanks are crucial for allocating safe drinking water,
but varying operational processes and infrequent maintenance can result
in water quality degradation, including disinfectant residual loss,
sediment accumulation, bacterial growth, and potential contamination.
This study assessed how the physical, chemical, and hydraulic characteristics
of representative chlorinated DWDS tanks relate to bacterial communities
in water and sediment; investigated water quality variation by depth
within tanks; and explored the infrastructure and management characteristics
influencing bacterial community composition in tanks. Bulk water and
sediment samples were collected from seven tanks in a chlorinated
DWDS system, and 16S rRNA gene amplicon sequencing was used to characterize
the bacterial community. Bulk water and sediment communities were
distinct, dominated by Alphaproteobacteria and Gammaproteobacteria,
respectively. Spatial variations as a function of distance from the
treatment plant, tank-specific characteristics, and sediment accumulation
were found to shape bacterial communities within tanks. Total coliforms
and Escherichia coli were undetectable
in all water samples, but genetic signatures indicated the presence
of multiple genera associated with opportunistic pathogens (OPs).
This study aims to establish a deeper understanding of the bacterial
community within DWDS tanks and the impact that tank conditions and
characteristics have on DWDS water quality.