CHAPTER XI 

 THE SANITARY EXAMINATION OF WATER-SUPPLIES 



ON account of the important interests at stake, 

 sanitary examinations of water-supplies should be thor- 

 oughgoing and complete as far as it is practicable. It is 

 not sufficient to determine whether pollution of drinking- 

 water has actually occurred: the inspection should 

 extend to possible future pollutions and the value of 

 sources of supply judged accordingly. 



Streams that 'once supplied pure water are now grossly 

 polluted by towns and cities that have grown up within 

 recent years. The expanding limits of cities and the 

 development of industries are calling for greater and 

 greater quantities of pure water and are disposing of 

 a constantly growing volume of waste. The problem 

 is thus complicated in both directions. Its solution must 

 be found ultimately in accordance with the statement 

 made by Mason that "a land should be looked upon as 

 watered by its smaller lakes, its springs, and its brooks, 

 and sewered by its great, especially its navigable, 

 rivers. Its water-sources should be protected by law 

 with exceeding care, and no river or stream should be 

 added to its list of drains except after proper consider- 

 ation by the State Board of Health, followed by legis- 

 lative permission." 



Larger cities are carefully guarding the area from 

 which their drinking-water is drawn. In some instances, 



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