Evaluation of microbial and chemical contaminant removals in different stormwater reuse systems

Although stormwater is considered an alternative water source, it has not been widely used yet most likely due to unclear benefits and cost of stormwater reuse as well as the concern about the presence of microbial and chemical contaminants in raw and treated stormwater. In this study, we analyzed the occurrences of various pathogens, antibiotic resistance genes (ARGs), and nutrient contaminants in raw and treated stormwater samples from two stormwater reuse facilities as well as city water irrigation and lake water irrigation systems. We detected various ARGs in stormwater samples, but they were also found in lake water and city water control samples. Since ARGs are naturally present in various bacteria including both pathogens and non-pathogens, detection of ARGs does not necessarily raise public health concerns. We also detected several viral pathogens, but they were most likely inactive/damaged, and therefore, not infectious. The levels of nutrients were generally low in the stormwater samples collected in this study. As a result, we did not see significant differences in the nutrient levels between before and after treatment. The running costs at the two stormwater reuse facilities were both cheaper than the irrigation facility that uses city water. Based on the data collected in this study, using treated stormwater for non-portable purposes such as irrigation could be a reasonably safe and sustainable alternative practice that is comparable to using lake or city water. Stormwater reuse can be economically beneficial and environmentally friendly.