es of
the body, and that distilled water fails to supply the necessary mineral
matter. This is an erroneous assumption, as the mineral matter in the
food is more than sufficient for this purpose. When water is highly
charged with mineral salts, additional work for their elimination is
called for on the part of the organs of excretion, particularly the
kidneys; and furthermore, water nearly saturated with minerals cannot
exert its full solvent action.

In discussing the immediate benefits resulting from improvement of
water, Fuertes says:[92]

"Immediately after the change to the 'four mile intake' at Chicago
in 1893, there was a great reduction in typhoid. Lawrence, Mass.,
showed a great improvement with the setting of the filters in
operation in September, 1893; fully half of the deaths in 1894 were
among persons known to have used the unfiltered canal water. The
conclusion is warranted that for the efficient control of the death
rate from typhoid fever it is necessary to have efficient sewerage
and drainage, proper methods of living, and pure water. The reason
why our large cities, which are all provided with sewerage, have
such high death rates is therefore without doubt their continuance
of the filthy practice of supplying drinking water which carries in
solution and suspension the washings from farms, from the streets,
from privies, from pigpens, and the sewage of cities.... And also
we should recognize the importance of flies and other winged
insects and birds which feed on offal as carriers of bacteria of
specific diseases from points of infection to the watersheds, and
the consequent washing of newly infected matter into our drinking
water by rains."

There is a very close relationship between the surface water and that of
shallow wells. A shallow well is simply a reservoir for surface water
accumulations. It is stated that, when an improved system of drainage
was introduced into a part of London, many of the shallow wells became
dry, indicating the source from which they received their supply. Direct
subterranean connection between cesspools and wells is often traced in
the following way: A small amount of lithium, which gives a distinct
flame reaction, and a minute trace of which can be detected with the
spectroscope, is placed in the cesspool, and after a short time a
lithium reaction is secured from the well water.