A review on chlorination of harvested rainwater

The supply of safe drinking water to rural communities has always been challenging, unlike in most large cities where government authorities have constructed central water supply systems. In many rural areas, primary water sources such as surface water and groundwater are at risk of contamination with rapid agricultural and industrial growth and climate change-related issues. Rainwater harvesting is an ancient practice for rural communities, and the momentum around its use is continually growing in recent years. However, the lack of sustainable treatment facilities on a small scale encourages dwellers to consume harvested rainwater (HRW) without any treatment even though drinking untreated HRW may have multiple health impacts in many cases. There are several methods of treating HRW. While chlorination is extensively used to disinfect water in large volumes, e.g., central drinking water supply systems), it has not been widely adopted for treating water on a small scale. We present a scoping review to explore whether chlorination could be a viable option for disinfecting HRW at a domestic level. It is found that inadequate treatment prior to chlorine disinfection could produce chlorine disinfection byproducts (DBPs). Limited data on DBP concentrations in HRW are available to assess its health implications. Based on this review, it is argued that chlorination could be an option for treating HRW at a domestic level when limitations associated with this method (such as safe storage, appropriate sustainable technology, and lessening DBPs by lowering total organic carbon before chlorination through other treatment methods) are resolved.