MICHIGAN ACADEMY OF SCIENCE. 
131 
pending danger.” In this same essay, in discussing tlie dangers arising 
from animal excreta, the important statement is made that decompos¬ 
ing animal substances are highly dangerous, even Avhen in minute quan¬ 
tities; and that filtered sewage though clear and transparent may carry 
with it the germs of disease. 
In addition to freedom from disease-producing organisms and to the 
standard just stated in reference to chemical composition, wholesome 
water should be clear or essentially free from all matter in suspension, 
and as noted above, not be open to the suspicion that it contains sewage 
or other material which may lead to prejudice against its use for 
drinking purposes. This last standard which it seems desirable to 
establish, may perhaps, by some persons, be considered as ultra-ideal, 
when practical considerations are taken into account, but it is cer¬ 
tainly reasonable to demand that drinking water should not contain 
sewage or other suspicious ingredients, even though the microscope 
fails to reveal the presence of disease-producing germs. 
In order to establish an ideal towards which persons in charge of 
the water supplies of cities may strive to approximate, it should also 
be born in mind that temperature has an important bearing on the 
wholesomeness of water used for drinking. While the habits of in¬ 
dividuals in this connection are not under the control of municipalities, 
it is obvious that if the water supplied to a city is of such a tempera¬ 
ture as to meet reasonable desires, the use of iced water particularly 
during hot weather would be greatly decreased and a danger to the 
general health of a community thus lessened. In this connection the 
desirability of providing reservoirs Avith covers, to be considered below, 
is worthy of consideration. 
SOURCES OF MUNICIPAL AVATER SUPPLY. 
The sources of Avater supply available for the use of cities may be 
classified as (1) rain water, (2) shalloAv Avells and cold springs,* (3) 
deep wells and warm or hot springs, and (4) streams and lakes. 
Rain Water: In certain instances the only available supply of water 
for domestic use is rain. So far as I am aAvare no municipality in the 
United States endeavors to store rain Avater for public use, but indi¬ 
viduals construct cisterns, etc., for themselves. The amount of Avater 
an individual provides for his OAvn use or for the use of a household, 
etc., is a private matter, but the healthfulness of the supply is of public 
concern. Intelligent supervision of cisterns when used as a means of 
domestic Avater supply, thus becomes as legitimately a matter of mu¬ 
nicipal supervision as the safeguarding of wells Avhen utilized in a 
similar way. 
Rain, in falling through the air, washes from it dust particles in¬ 
cluding living organisms, and in thickly settled regions, or whenever 
disease-producing germs are disseminated through the air, may reach 
the earth in an unwholesome condition. Its liability to contamination 
is enhanced as it flows over roofs, etc., and on entering a cistern, the 
*The classification of springs uses here is arbitrary, but suggestive in reference to the domestic uses of 
such water supplies; by cold spring is meant one not sensibly influenced by the earth’s internal heat, 
and in general conformable in temperature, to the mean annual temperature of the surface at the 
locality where it is located, and in the case of warm and hot springs the reverse of these conditions 
obtains 
