CHAPTER ONE
1.0    INTRODUCTION   
1.1    Background of Study
Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability (Kulshreshtha, 2008). A report, issued in November 2009, suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.
Water plays an important role in the world economy. Approximately 70% of the freshwater used by humans goes to agriculture (Baroni et al., 2007). Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of long-distance trade of commodities (such as oil and natural gas) and manufactured products is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of chemical substances; as such it is widely used in industrial processes, and in cooking and washing. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, and diving.
Not only quality but also quantity of domestic water supplies impacts on human health. The review by Esrey and Habicht (2006) of 65 epidemiological studies on the health effects of improved water supplies and sanitation facilities indicates that quantity of water is often more important than quality, particularly in heavily contaminated environments.
The human body has 55% to 78% water depending on body size. The percentage of water observed in different body parts are as – muscular tissues 75%, brain contains 90% water, bones 22%, and blood 83%. Since, water is one of the essential components required to our body, it is important to assess the quality of water, which is being used for household activities as well as consumption whether it is actually reliable and safe for health of the consumers. Water portability refers to the quality of water that can be safe for consumption and use with no risk of adverse health effects.
Many studies have been carried out worldwide for checking the quality and safety of drinking water. Kurup et al. (2010) have carried out the microbial and physiochemical analysis of water samples by taking biofilm samples from residential areas in Georgetown, Guyana, discovering the most prevalent species to be Lactobacillus and the least prevalent species to be Salmonella sp. Zvidzai et al. (2007) carried out a study on microbiological assessment of rural drinking water in Zimbabwe.
Smeets et al. (2008) have found that absence of indicator organisms in drinking water does not guarantee microbial safety. Therefore, the water utilities are implementing water safety plans (WSP) to safeguard drinking water quality. Quantitative microbial risk assessment (QMRA) can provide objective quantitative input for Water Safety Plans. Prasai et al. (2007) have evaluated quality of water from different sources (tap, stone spout, tube well and well) from Kathmandu valley by utilizing Heterotrophic plate counts and Coliform counts extensively as basis for regulating microbial quality of drinking water. Regulatory parameters were found to be much above the WHO guideline values. This study showed that most natural water sources are highly contaminated. The detection of pathogenic enteric bacteria in different sources of drinking water depicted for water borne epidemics situations there.
Nagpal et al. (2011) have examined the drinking water for the presence or absence of Salmonella, Citrobacter, E. coli and Vibrio species in the Indira Sagar/Omkeshwar project affected areas and rehabilitation/ resettlement colonies of Sardar project in Madhya Pradesh. Tambekar et al. (2008) revalidated the testing methods for assessing microbial safety of drinking water in the villages of Amrawati district of Maharashtra for using bacteriological analysis with the help of Mutiple Tube fermentation technique to determine most probable number (MPN), Membrane filter techniques, Eijekamn’s test for thermotolerant coliform and Manja’s Rapid hydrogen sulphide test for detection of fecal contaminations in drinking water.