B046 Office drinking water
Microbiological drinking water quality in a high-rise office building of Hong Kong
Brief:
Microbiological water quality of the drinking water is highly associated with enteric
diseases. In this study, the water quality for the water supply system of a typical highrise
office building in Hong Kong was examined. A comparison of the bacteria levels
between the high and low water consumption periods was made. Tap water samples (0.1
L) were collected at the water supply system every 4 hours from 08:00 to 20:00 in a
normal working day that had a working day prior and after and a normal working day
that followed a long weekend. The results showed that the bacteria counts ranged from
80 to 1000 CFU L−1. It was found that the bacteria counts at a time after a low water
consumption period were significantly higher. This was probably due to the
multiplication and accumulation of bacteria in the water storage system in low
occupancy hours. Among the bacterial genera identified, 59% were gram-positive
bacteria genera composed of Bacillus (6%), Micrococcus (28%), Staphylococcus (6%)
and others (19%), and 41% were gram-negative bacteria genera including Pseudomonas
(13%), Escherichia coli (1%) and others (27%). A low quantity of the faecal indicating
bacteria, E. coli, was detected with a relative abundance of 0.5-1.4%. Its presence was
probably due to bioaerosols generated from nearby WC flushing. Future investigations
regarding the probable transmission through a water supply system of high-rise office
buildings in sub-tropical climate were recommended.
Further Information:
Chan WY, Wong LT, Mui KW, 2007. Microbiological drinking water quality in a high-rise office building of Hong Kong, The 33rd CIBW062 International Symposium of Water Supply and Drainage for Buildings, 19-21 September, Brno, Czech Republic, Session C4, pp. 149-156.