The Sanitary Engineer and the Public Health. 
41 
innately most of onr cities are forced to depend upon just such sources, 
either by impounding rain water in storage reservoirs, or by drawing 
their supply direct from some nearby stream. That which is caught in 
surface tanks is polluted by washings of the ground surface and by the 
absorption of dust, bacteria, etc., from the air during precipitation, and 
when allowed to stand in the reservoir the organic matter is subject to 
decay. Biver water is likely to be contaminated, not only from the sur- 
face washings during rain storms, but also by the discharge of domestic 
sewage by towns higher up the stream, and as the population of a dis- 
trict increases the danger from this source of infection grows greater. 
Rivers furnish such a convenient source of water supply that it is natural 
to turn to them for what is needed in large quantities. They also fur- 
nish an easy method of disposing of the wastes of a crowded city, both 
domestic and manufacturing, and the amount of, dilution is rarely suffi- 
cient to render the water fit for domestic use. You would think that 
no city would be so foolish as to waste its sewage at a point above the 
intake of its own water supply, but such is not by any means on unknown 
circumstance. What wisdom would suggest should be done with regard 
to the relation between the discharge of sewage and the intakes for the 
water supply of a given city the rights of other communities lower down 
the stream should compel a city to do if their supplies are likely to be 
affected thereby. The old idea that running water purifies itself is now 
known to be a fallacy, and it is known that pathogenic bacteria will 
survive for days, weeks, even months, in water that may even be in 
motion, and that, too, under conditions of temperature that it would 
seem to be impossible for them to withstand. 
The census reports tell us that at least one-seventh of the deaths in the 
United States are due to diarrheal diseases, to typhoid fever, malaria or 
intermittent fever — the germs of which are water borne. In 1890 there 
were 120,000 deaths from these diseases, all of which, we may very prop- 
erly charge to impure drinking water. In 1890 the deaths from typhoid 
fever amounted to fifty-six deaths in 100,000 persons population, the dis- 
tribution being about the same for small as for large communities. In 
1896 the deaths in the larger cities amounted to thirty per 100,000 from 
this disease, as an average, though there were many variations from the 
average. In Chicago, for example, typhoid fever carried off 83 in every 
100,000 in 1890, 160 per 100,000 in 1891, 104 per 100,000 in 1892, 
while in 1894, 1895 and 1896 the deaths from, this cause amounted to 
only 31, 32 and 48 for the respective years — the difference being directly 
traceable to the fact that in 1893 the city moved the intakes for the 
water suuply two miles further out into the lake, making the distance of 
these intakes four miles from shore instead of two miles. This was a 
purely engineering operation, and the reason for the drop in mortality 
