The Supply and Uses of Water 



187 



With such facts it is a simple matter to calculate the amount 

 of water that must be provided for a city of 100,000. Assume 

 for such population an individual allowance of twenty gallons 

 a day; the total daily supply must be at least two million 

 gallons. This is less than the average daily consumption per 

 individual in most communities. The following table gives 

 the quantities consumed in several large cities together with 

 the percentage of water delivered through meters. 



74. Public control of water supply. It is not difficult to 

 see why in towns and cities private control of the water supply 

 has been replaced largely by public control. The population 

 has increased at a remarkable rate and concentrated more and 

 more in cities where a local and private supply is impossible. 

 The conditions brought about by city life make local wells a 

 menace to life and health by exposing them to contamination 

 by filth-laden surface water and drainage. After many epi- 

 demics of typhoid fever and other diseases had been demon- 

 strated to be due directly to polluted wells, people began not 

 only to suspect, but also to abandon this source of supply. 



Exercise : Local conditions. There are other conditions in par- 

 ticular localities, which make necessary the transfer of the water 

 supply from private to public control and supervision. These should 

 be included in the study of the local water supply outlined on page 223. 

 The conditions deserving special mention include irregular rainfall; 

 a limited watershed, making a large number of private wells with 

 sufficient supply impossible ; the multiplying uses of water in domestic, 



