B042 Microbiological water quality

A microbiological assessment for drinking water quality

Brief:

Microbial contamination of a water distribution system of a building would associate with some enteric diseases. This study investigated the microbiological water quality of a drinking water stored in a water distribution system of a typical high-rise office building of Hong Kong. The heterotrophic plate count (HPC) bacteria in water samples (0.1 L) collected in a water distribution system every 4 hours from 8:00 to 20:00 for 2 days were determined. The results showed that the bacteria counts ranged from 80 to 320 CFU L^-1, with an average of 154±92 CFU L^-1. Significantly higher bacteria counts were recorded in the sample collected at 8:00 when compared with the samples collected at afternoon (p<0.05), probably due to dilution of bacteria concentration. The isolated bacteria in the water samples were identified; 57% were gram-positive bacteria genera composed of Bacillus (8%), Micrococcus (28%), Staphylococcus (13%) and unidentified isolates (8%), and 43% were gram-negative bacteria genera including Pseudomonas (18%), Escherichia coli (2%) and unidentified isolates (23%). A low level (20 CFU L^-1) of the faecal indicating bacteria, E. coli, was detected and it may probably due to the existing cleaning practice. This paper addressed the needs of microbiological assessments of potable water supply systems in high-rise buildings of Hong Kong.

Further information:

Chan WY, Mui KW, Wong LT, 2007. A microbiological assessment for drinking water quality, The 1^st Hong Kong-Taiwan Workshop on Water Systems in High-rise Buildings, 25 Jun, Hong Kong pp. 36-41.