Effective removal of microbial contamination from harvested rainwater using a simple point of use filtration and UV-disinfection device

There is a growing interest in the utilisation of harvested rainwater as an alternative water source. This study summarises an evaluation of the water quality obtained for privately-owned cisterns sampled in Tucson, AZ and the feasibility to obtain high-quality water from harvested rainwater by fitting cisterns with Point of Use (POU) filtration and UV disinfection devices. Of the 11 cisterns sampled, 30–50% tested positive for E. coli, 100% contained Enterococci and a few tested positive for lead at concentrations above the MCL. All physicochemical and microbiological constituents analysed were present at higher numbers in the summer than in the winter. The POU devices sufficiently cleared the harvested rainwater of total coliforms, E. coli, and Enterococci but performed marginally with respects to improving turbidity and heterotrophic bacteria.