Risk of Contamination in Rooftop Rainwater Harvesting
There has been a growing interest, especially in developing nations like India, in rooftop rainwater harvesting as an alternative source of freshwater. Rooftop rainwater harvesting involves the collection and storage of water from rooftops. Generally, rainwater is free from impurities except those picked up by rain from the atmosphere, but the quality of rainwater may deteriorate during harvesting, storage and reuse. Microbiological Contamination Microbial contamination of collected rainwater indicated by E. coli (or thermotolerant coliforms) is quite common, particularly in samples collected shortly after rainfall. Many research publications from different regions reported 24- 92% of harvested rainwater samples positive for microbial contamination. Higher microbial concentrations are generally found in the first flush of rainwater, and the level of contamination reduces as the rain continues. Heavy Metals Rainwater is slightly acidic in nature and