Academic journal article Journal of Environmental Health

Risk Assessment of Rooftop-Collected Rainwater for Individual Household and Community Use in Central Kerala, India

Academic journal article Journal of Environmental Health

Risk Assessment of Rooftop-Collected Rainwater for Individual Household and Community Use in Central Kerala, India

Article excerpt


Though 70% of the earth's geographical area is covered by water, only 1% of it is potable; the rest is unsafe for consumption. Lack of investment, growing water demand, overexploitation of existing sources, pollution, and maintenance problems make the supply of potable water in developing countries extremely difficult to obtain. The availability of an adequate supply of safe water is fundamental to the development process in all sectors with benefits such as improved labor productivity (Gadgil, 1998). The microbial quality of many drinking water sources in India, both groundwater and surface water, is affected by human activities (Pushpangadan, 2003) and it is reported that nearly 44 million people in India are directly affected by water quality problems, either due to bacteriological or chemical pollution (Nigam, Gujja, Bandyopadhyay, & Talbot, 1998).

Due to decreasing supply and the ubiquitous contamination of surface and groundwater resources by microbial and chemical contaminants, rainwater harvesting has become more relevant now in areas that enjoy high rainfall. Rainwater harvesting can provide a renewable supply of natural, soft, clear, and odorless water that could be used for a range of purposes and could represent the primary source of household water in some areas. Governmental agencies across the world are now introducing policies to promote increased use of rainwater. In India, awareness is growing of the potential of rainwater harvesting to meet the demand of safe water throughout the country, especially in rural locations. Several state governments including in Kerala have introduced legislation that makes it obligatory to incorporate rooftop harvesting systems in newly constructed buildings in urban areas. Governments are also providing subsidies to promote the use of rainwater harvesting systems.

The National Sample Survey Organization (1999) has reported that the most significant risk to human health related to drinking water quality is from microbiological sources through fecal contamination. In general the quality of rainwater is not treated for bacteriological quality and is assessed at the household level because of the presence of leaves and other materials such as mosquito larvae, insects, rodents, frogs, etc. The World Health Organization (WHO) proposed appropriate treatment techniques to use harvested rainwater as a safe drinking water source (WHO, 2006). Researchers revealed the value of solar disinfection (SODIS) as a low-cost, sustainable, and simple method of treating contaminated water in developing countries (Acra, Jurdy, Muallem, Karahagopian, & Raffoul, 1989; Acra, Raffoul, & Karahagopian, 1984; Sommer et al., 1997).

Though Kerala receives adequate annual rainfall, many parts of the state are experiencing severe drinking water shortages due to poor water management. As a proactive measure, the government of Kerala is promoting rainwater harvesting in rural and urban areas for household use and community use in schools. Monitoring of this rooftop-collected water, however, is not carried out. Hence our study had an objective to determine the bacteriological and nutrient quality of rooftop-harvested and stored rainwater for individual household use as well as for community use in rural and urban settings. General bacterial flora of rooftop-collected water were characterized and the risk assessment of these strains was carried out by drug resistance analysis.


Collection of Samples

The rooftop-harvested rainwater stored in ferrocement tanks (see photo above) was collected from rural and urban areas of Kottayam, Alappuzha, and Eranakulam districts of Kerala. Ferrocement tanks are made of a thin sheet of cement mortar reinforced with a cage of wire mesh and steel bars. The rainwater from the rooftop is directed to the tank by gutters and polyvinyl chloride pipes to the inlet of ferrocement tanks. …

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