Use of the best source water quality that can be obtained economically is a concept that has been advocated by public health authorities. In the past time, the 1962 Public Health Service Drinking Water Standards (Public Health Service, 1969) stated, “The water supply should be obtained from the most desirable source which is feasible, and effort should be made to prevent or control pollution of that source. If the source is not adequately protected by natural means, the supply shall be adequately protected by treatment”. The fundamental concept of acquiring the best quality of source water that is economically feasible is an important factor in making decisions about source selection and treatment (Logsdon et al., 1999).Water commonly is not present at the locations and times where and when it is most needed. As a result, engineering works of all sizes have been constructed to distribute water from places of abundance to places of need. Regardless of the scale of the water supply system, development of either ground water or surface water can eventually affect the other (Winter et al., 1998).
The source of the raw water may be a river, lake, artificial reservoir, groundwater, and in some cases, reclaimed sewage or seawater. The evaluation and selection of the proper water source should be based on the following issues: (1) quantity of water required, (2) quality of the raw water, (3) climatic conditions, (4) potential difficulties in constructing the intake, (5) operator safety, (6) providing minimal operations and maintanance costs for the treatment plant, (7) possibility of future contamination of the water source, and (8) ease of enlarging the intake if required at a future date (Kawamura, 2000).Water utilities and their engineers need to consider use of alternative sources when a new treatment plant or a major capacity expansion to an existing plant is being evaluated, or when a different and more costly approach to treatment is under study. When treatment costs are very high, development of a source of higher quality may be economically attractive. Among the options are (Logsdon et al., 1999):
In some instances, water utilities may be able to avoid investing large sums on treatment by choosing an alternative to treatment. One option that may be available to small water systems is to purchase water from another utility instead of treating water. This option might be selected when treatment requirements are made more stringent by regulations, or when capacity of the system has to be expanded to meet demand. This may be a particularly attractive choice when a nearby larger utility has excess capacity and can provide treated water of the quality needed (Logsdon et al., 1999).Other alternatives to increased capacity for water treatment may occasionally be available. If the water utility needing to expand has not adopted universal metering for domestic water customers, the system demand might be significantly reduced if universal metering was put in place. Customers on flat rates may have little overall incentive, and no identifiable economic incentive, to be prudent in their use of water (Logsdon et al., 1999).When distribution systems have high rates of water loss, a program of leak detection and repair may result in increasing the amount of water available to consumers without an increase in production. Examination of alternatives to treatment may in many instances reveal the existence of no practical or economically attractive alternatives to treatment of a presently used or a new water source. In such circumstances, modified, expanded, or new water treatment facilities will be necessary (Logsdon et al., 1999).
