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Other sanitarians consider that hard water is better than soft or
distilled water for drinking purposes. Rector (1916) remarks "the
weight of evidence is in favour of the use of a natural hard water
containing a moderate amount of mineral." Opitz draws from a
large amount of statistical data the following conclusions: "Communities
with a very hard water are better as regards frequency of
dental trouble in registrants for military service, among disability
claimants and in school children. Also there was a better body weight
and degree of robustness among registrants for military service. The
vitality of the newborn was better. There were fewer signs of nervous
excitability in infants, school children and those insured for disability.
There was a slight advantage as regards size of infants and school
children and with reference to mortality from tuberculosis."
Thresh, Beale and Suckling (1949) conclude that the evidence
that excessively hard waters cause kidney disease, dyspepsia, etc., is
most unreliable and state that " a French Commission arrived at the
conclusion that a moderately hard water was the best, and that persons
residing in districts supplied with such water had a better physique
than those living in districts where soft water was used." A Vienna
Commission expressed the same opinion.
Other evidence is derived from animal experiments. Thus Myers
(1925) experimented on white mice, white rats, rabbits, dogs, calves,
pigeons and chickens as to the relationship between hard water and
growth. These experiments show similar equivocal results to the
human studies already quoted.
White mice and white rats show no striking difference in growth
and appearances between the groups fed on grain and meal but with
a natural hard water in one instance and distilled water in the other
group.
Young rabbits, calves and a few dogs grow faster and are heavier
when natural hard water instead of distilled water is the supplement
to the diet. Similar results are obtained with chicks and when salts
are added to distilled water to simulate natural hard water growth
in both groups is equal.
These experiments show that in no instance do animals on distilled
water develop better than on hard water and the reverse is true in
several conditions.
In fact most investigations show that hard waters are a valuable
source of calcium when the diet is otherwise low in this mineral.
Effect on incidence of stone in the urinary tract
Experiments on animals give no evidence that hard water is
by itself a factor in urinary concretion formation.
John T. Myers (1925), quotes an early study by Studewsky, in
which various foreign bodies are introduced into the urinary bladders
of dogs where they remain for periods of one to three months. The
objects include polished glass beads, pellets of gutta percha, hollow
jug shaped glass objects, rolls of lead wire, balls of gum and irregular
pieces of tin plate.
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