The Impact of Rooftop Water Storage Tanks Cleaning on Premise Plumbing Water Quality and Microbiome | 頂樓水塔清洗對於建築供水系統水質及菌群之影響

Indirect premise plumbing is a common practice for water distribution in Taiwan. However, the extended water residence time in indirect premise plumbing system may encourage bacterial regrowth. In addition, natural organic matter or sediments in roof top storage tank/tower may also react with residual chlorine and generate additional disinfection byproducts (DBPs). A year long water monitoring task was conducted in a building with indirect water supply system including concrete roof top storage tank. The roof top storage tank was cleaned twice in the sampling period follow the Taiwan EPA's recommendation. Chemical parameters, heterotrophic plate counts (HPC), and planktonic microbiome from both tank influents and effluents were analyzed intermittently before and after storage tank cleaning. The results showed that after cleaning, the chlorine decay, and trihalomethanes formation were decreased in the tank effluent. However, HPCs were increased in the beginning along with planktonic microbial population changes. After tank cleaning, it will take 2 to 3 weeks before the microbial population was stabilized again. © 2020, Chinese Institute of Civil and Hydraulic Engineering. All right reserved.