96 ILLINOIS ACADEMY OF SCIENCE 
The principal evil growing out of the extensive installation 
of modern sewerage systems is the pollution of streams. Many 
streams in the United States have been so grossly polluted as 
to be fit for no other purpose than as a receptacle and an open 
drain for putrefying wastes. This situation is due entirely 
to the fact that benefit from the installation of adequate sewage 
treatment works accrues to the down stream neighbors of a 
community using the sewerage rather than to the community it- 
self. Once ina while a city may modify its method of sewage 
disposal in order to prevent polluting its own water supply, 
and befouling its own water front; but rarely does a city of its 
own volition do anything to protect the water supply or the 
water front of its neighbors. 
It would therefore appear very clearly that the matter of 
sewage disposal, has an inter-community relation, and by 
virtue of this fact, becomes a matter that should be regulated 
by the state, or in the case of interstate streams, by the nation. 
By way of summary it may be said that with a pure public 
water supply serving all of the people in a given community 
to the exclusion of private supplies less pure, and with a com- 
plete sanitary sewerage works serving all the people and used 
to the conclusion of human waste disposal methods less 
efficient, typhoid fever will be virtually wiped out, and other 
communicable diseases of an intestinal character will be re- 
duced in like proportion. Complete extermination of these 
diseases may be expected when food supplies, more particu- 
larly milk, are under absolute sanitary regulation, and when 
persons harboring the germs of this disease, may be properly 
controlled. 
