Microbiology of Water

Microbiology of Water

	Microbiology of Water Water is indispensable for life. The basic human physiological requirement for water is about 2.5litres per day. This drinking water should be free from chemical as well as microbial contaminants, since the potential of contaminated water to transmit disease is very high. Potable waters are normally tested for their quality based on various factors because water quality is very important in both health and industrial aspects of economy. The most frequently used indicator organism is the normally nonpathogenic coliform bacterium, Escherichia coli.
The great solvent power of water makes the creation of absolutely pure water a theoretical rather than a practical goal. The problem, therefore, is one of determining what quality of water is needed to meet a given purpose and then finding practical means of achieving that quality. The problem is further compounded because every use to which water is put-washing, irrigation, flushing away wastes, cooling or making paper- adds something to the water. The term water pollution is referred to any type of aquatic contamination between the following two extremes: (1) a highly enriched, over-productive biotic community, such as a river or lake with nutrients from sewage or fertiIiser (cultural eutrophication) and (2) a body of water poisoned by toxic chemicals which eliminate living organisms or even exclude all forms of life.
A vague understanding of the need to protect water systems that are used for drinking, from contamination with waste and wastewater is documented in historic documents, for instance in the Bible. The regular outbreaks of diseases like typhoid fever and cholera were thought to be related not to water, but to local atmospheric conditions. Despite this misleading theory, John Snow concluded from epidemiological evidence that a drinking water pump was the cause of cholera outbreak in London. By removing the handle of the pump in 1854, he was able to stop the cholera outbreak.
The necessity of resource protection and drinking water treatment became evident when the connection between bacteria in drinking water and the outbreak of various diseases was made. Today, in most industrialised countries, drinking water is ranked as food, and high standards are set for its quality and safety. The strict requirements for microbiological factors specify that bacteria content should be very low and that no pathogenic microbes should be detectable. The fear of classic waterborne infectious diseases like cholera and typhoid fever have been lost in developed countries.
	Water may contain various contaminants and pollutants and it is extremely difficult to obtain pure, potable water. Faecal contamination of drinking water supplies is a potential problem. Presence of disease causing pathogenic microbes is also common. In addition to microbial contaminants, organic and inorganic colloids are also present in water. Clays, microbial debris, and reduced iron and manganese compounds are also common. When water is obtained from open surface water bodies, floating or large suspended solids such as leaves and branches may be present. Hence, to render water fit for drinking and domestic use, treatment of the water is necessary. The purpose of water treatment is to convert raw water into drinking water suitable for domestic use.

Most important is the removal of pathogenic organisms and toxic substances like heavy metals which cause serious health problems. Other substances to be removed include suspended matter causing turbidity, iron and manganese compounds imparting a bitter taste and excessive carbon dioxide corroding concrete and metal parts.

Drinking water is obtained from different sources, and various impurities ranging from branches of trees to invisible microbes may occur in these waters and have to be removed before the water is supplied to the public. To render the water safe for drinking, it has to be treated properly.

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