WATER QUALITY: STANDARDS and REGULATIONS

Water quality refers to various physical, chemical, microbial and biological characteristics of water with reference to laid down set of regulations and standards. Physical, chemical, microbial and biological characteristics of water depend on a number of factors like the soil composition, absorption capacity of soil, the climate of the region, the rainfall received, geological conditions, pollution level and activities of man in a particular region. Different water bodies and sources (groundwater, lake water, etc.) have different standards of quality. The standards of water quality also depend on the nature of use of water; industrial use, human consumption, animal use. The importance of supplying water of adequate quality for human consumption is becoming increasingly important. The water crisis in the world is enhancing and has become a matter of dispute between nations. The problem of safe drinking water is far more pronounced in developing nations where people are being affected by waterborne diseases and contaminants.

WATER CONTAMINATION

The major causes of water contamination are human actions and industrial wastes which make it unfit for human consumption. Even the natural water is never chemically pure. The rain droplets form on hygroscopic nuclei particles such as sodium chloride, sulphur trioxide. Such drops can dissolve various gases like (carbon dioxide) present in the atmosphere. This can cause acidic rain in regions where the content of gases is high due to the pollution caused by human actions and industries. Another way in which water gets contaminated is via dissolution of solids and minerals present in rocks by chemical weathering. Agents which cause chemical weathering are carbonic acid, humic acids, etc. Oxidation of minerals found in rocks and soil also adds dissolved solids to water. Weathering of soil adds salts to water thus causing high saline concentrations in areas with poor drainage, high evaporation rates or less rainfall. With increasing depth of an aquifer, the circulation rate of groundwater decreases leading to increased dissolution of minerals. Thus contamination due to minerals increases with depth. The upper region has higher concentration of bicarbonates while the lower stratum is rich in chlorides. This distribution of ions in strata is grouped in hydrochemical facies. Hydrochemical facies are "distinct zones which have anion and cation concentrations which can be described within certain composition categories" (Freeze and Cherry, 1979).

The degradation in the quality of water is a result of human activities, industrialization, changes in trends of land use and economic development. Industries discharge large amounts of toxic waste into water bodies like rivers, lakes, etc. causing chemical contamination. Besides, the wastes produced by humans and animals also contaminate water. Contaminated water acts as a breeding ground for disease carriers (mosquitoes) and waterborne pathogens (virus, protozoa, worms, bacteria, etc.). Contaminated water is the cause of water related and water based diseases.

ASPECTS OF WATER QUALITY

Water quality is a term which refers to qualities of water which are desirable and in reference to the guidelines and standards laid down by various organizations like WHO, EPA, etc. Water Quality covers various components and aspects:

Microbial aspects

Microbial considerations of drinking water refer to the type and number of pathogenic micro organisms present in water. The main sources of introduction of micro organisms in water are human and animal faeces. The micro organisms can be bacteria, protozoa, virus and helminthes. Increase in the concentration of pathogens at any time causes outbreaks of waterborne diseases. Infectious diseases caused by pathogens are the most common health risk related to drinking water. Besides the faecal contamination, some microbes such as Legionella are found in pipes of water distribution systems, some like guinea worm are found in water source. Some microbes infect through skin when water is used for bathing, washing, etc. Schistosomiasis is an example of such disease. The occurrence of pathogens in an area depends on certain factors like characteristics of catchment area, human activities, animal excreta, municipal sewage water, contaminated water from agricultural and industrial areas and the types of animals having direct access to water sources. E. coli is the faecal indicator bacteria used to ascertain microbial quality of water. It should not be present in drinking water.