CHAPTER VI
SOURCES OF WATER-SUPPLY
Having arrived at the quantity of water necessary to supply the needs of the average household, we must next investigate the possible sources from which this quantity can be obtained. Before the advantages of running water in the house are understood, a well is the normal and usual method of securing water, although in a few cases progressive farmers have made use of spring water from the hillsides. It is rare, indeed, for surface water, so called, to be used for purposes of water-supply until after modern plumbing conveniences have been installed. Then the use of surface water becomes almost a necessity because of the large volume of water needed. The only drawback to its use is its questionable quality. Without modern plumbing, a well meets the requirements of family life, but does not answer the demands of convenience. With modern plumbing, a well is found to be pumped dry long before the domestic demands are satisfied. The result is an attempt to secure an unfailing supply, and for this a surface supply is sought.
Let us divide, then, the possible sources of water for domestic consumption into two groups, those found under the surface of the soil and those found on or above the surface. In the first group will come wells and springs, and in the second group will come brooks, streams, and lakes.
Underground waters.
Springs result from a bursting out of underground waters from the confined space in which they have been stored or through which they have been running. Thus in Fig. 24 is seen how water falling on the pervious area a-b is received into the soil and gradually finds its way downward between impervious strata which may be clay or dense rock. At the point B, where the cover layer has, for any reason, been weakened, the pressure of the water forces its way upward and a spring is developed at the point C. Or, conditions may be as shown in Fig. 25, where the confined water, instead of being forced upward by pressure, flows slowly out from the side of a hill, making a spring at the point D, while the water enters the pervious stratum at the point a-b as before.
Fig. 24.—Diagram of a spring.