188 Introduction to the Study of Science 



municipal, and industrial activities ; the disposal of sewage ; the ne- 

 cessity for economy and universal distribution throughout the com- 

 munity ; and the belief that public interests are not always properly 

 conserved by private interests in control of public utilities. You 

 may find in your own locality other factors of importance. 



As a result of such conditions and others of a local nature, 

 the water supply in many places has been transferred to the 

 control of the municipality as one of the great public utilities, 

 in which private interests and management are undesirable. 

 This " free gift of nature," although it is seldom really free, 

 is now provided most conveniently for all purposes, and at a 

 minimum cost to every member of a community. Public 

 wisdom and enterprise are made responsible for the control 

 of the watershed, for collecting and conserving of the rainfall 

 on a given area, and for the distribution and economic use of 

 water in the community. The increase in public control of 

 this utility is shown by the fact that to-day there are more 

 than four thousand municipal water systems in the United 

 States, whereas at the beginning of the nineteenth century 

 there were only seventeen. 



II. THE WATER SUPPLY OF CITIES 



75. Conditions determining sources of supply. The 

 sources of the water supply of any community are determined 

 by the rainfall and by the character of the surrounding country ; 

 the utilization of such depends upon the social and financial 

 resources of the community. One community may look far 

 ahead and secure possession of a desirable watershed to provide 

 a supply that may be far in excess of current needs. Another 

 community may suffer want and several epidemics of disease 

 before it makes adequate provision for its present needs. 

 This is true of many a community to-day. Meanwhile the 

 most available sources are being preempted and utilized by the 

 more provident distant cities, although such sources may be- 

 long rightly to the near-by communities. 



