The term water quality is a widely used expression which has an extremely broad spectrum of meanings. Each individual has vested interests in water for his particular use, which may involve commercial and industrial uses or recreational pursuits. Since the desirable characteristics of a water vary with its intended use, there is frequently unsatisfactory communication among the users if water where quality is concerned. Thus in discussing a public supply, a housewife may declare the water to be of good quality, while a brew master considers the quality to be poor.
All other water uses must be subordinated to man's need for a healthful fluid for his consumption. Water for drinking and food preparation must be free from organisms capable of causing disease and from minerals and organic substances producing adverse physiological effects. To encourage man to drink this health-promoting liquid, the water must be aesthetically acceptable. For example, it should be free from apparent turbity, color and odor and from any objectionable taste. Drinking water also should have reasonable temperature. Such water is termed "potable," meaning that it may be consumed in any desired amount without concern for adverse effects on health.
HISTORICAL NEEDS FOR WATER
QUALITY CRITERIA:
Historically, fertile river valleys with abundant water seem to have been the centers for the beginnings of civilization. The greatest use of water was for irrigation and agricultural pursuits, while only the people consumed a small amount. The use of water for drinking and cooking was limited to that amount that people could carry from the well or the stram in their jugs, pots, and other vessels.
it seems a curious fact that, whole water is an absolute necessity for life, little was recorded by ancient historians regarding the quality of drinking water. Certain brief reference was made to boiling, filtering, sedimentation, and treatment of water with salts. Since man knew relatively little about disease, it must be concluded that any treatment had as its objective the improvement of the appearance or taste of the water. No definite standards of quality other than general clarity or palatability were recorded by ancient civilizations.
BACTERIOLOGICAL EXAMINATION
OF WATER:
The bacteriological examination of water is a rather recent development. Normally, fecal contamination is indicated by the presence of a group of organisms designated by the term "coliform." in the past; such organisms have been referred to in literature as B.Coli, Bacterium coli, Bacillus colon, Escherichia coli, or E coli. The term "coliform group" is the present connotation, and it implies that these organisms are a bacterial group of unknown dimensions rather than a single species.
In 1884 Escherich isolated from the stinks of cholera patient organisms, which he originally thought to be the cause, if those disease/ Further investigations, however, showed that similar organisms also were present in the intestinal tracts of healthy individual. From this beginning, the existence if the coliform organisms has come to be recognized as an inherent characteristic of the feces of man. Perhaps one-third to one-fifth of the weight of the average individual's is active viable coliform organisms. In terms of populations' equivalent, this amount to 200 * 10 exp 9 coliform cells per capita per day. The presence of these organisms in water may be interpreted to mean that such water has been contamination; it remained for Theobald Smith, about a decade later, to establish procedure in 1892 in their study of pollution of the Mohawk and Hudson Rivers .
