Abstract:
Rain-, ground- and municipal potable water were stored in low density polyethylene
storage tanks for a period of 90 days to determine the effects of long term storage on
the deterioration in the microbial quality of the water. Total viable bacteria present in the
stored water and the resultant biofilms, were enumerated using heterotrophic plate
counts. PCR and Colilert-18® tests were performed to determine if the faecal indicator collected throughout the study. The municipal potable water at the start of the study was
the only water source that conformed to the South African water quality guidelines for
domestic use. After 15 days of storage, this water source had microbiologically
deteriorated to levels considered unfit for human consumption. E. coli was detected in
the ground- and potable- water and ground- and potable biofilms periodically; whereas,
it was detected in the rain water and associated biofilms at every sampling point.
Imperfections in the UV resistant inner lining of the tanks revealed to be ecological
niches for microbial colonisation and biofilm development. The results from the current
study confirmed that long term storage can influence water quality and increase the
number of microbial cells associated with biofilms on the interior surfaces of water
storage tanks.
