The problems of water supply under field conditions are very different from those of the average city or town, even though the same fundamental principles apply to both. The city or town will in all probability make an extensive and careful survey of all water supply prospects and then choose that source which seems likely to offer the cheapest means of getting enough water that will be safe to use for drinking and other domestic purposes. Once the source is decided upon, expensive pumping and purification plants are erected and a complex distribution system is installed. A high degree of physical attractiveness is required in addition to the bacterial safety of the water so that the plant must be kept operating at a high degree of efficiency. This, of course, requires a trained staff of operators
