BACTERIOLOGY AND WATER 105 



of Health, however, points out that "with the 

 present increase in population the Great Lakes, 

 if they continue to be used as common sewers, 

 will soon become totally unfit for use as drinking 

 water, . . . and one of two alternatives must be 

 followed either every source of water-supply 

 must be filtered, or the sewage of the towns must 

 be efficiently purified before it is allowed to flow 

 into the lakes." 



Doubtless this seeming inertia of the citizens of 

 Chicago in the matter of filtering their water is 

 attributable to the fact that already the authorities 

 have expended eighty-five million dollars in their 

 waterworks and sewerage systems, which repre- 

 sents an investment of something over fifty dollars 

 per head of population, and that plans in connec- 

 tion with the great canal which has been described 

 as "the greatest feat of sanitary engineering in 

 the world," and to which reference has already been 

 made, will, when carried out, involve an expendi- 

 ture of thirty or forty million dollars more. In 

 the face of such burdens even so prosperous a 

 community as Chicago does not care to contem- 

 plate further capital charges, at any rate until the 

 unsatisfactory conditions shadowed by Dr. Egan 

 become more pressing in regard to the source of 

 their water-supply. 



The systematic investigations carried out in the 



