Water supplies differ greatly in purity and composition, and are of the
utmost importance in their effect upon the general health of a
household. There is nothing which requires to be guarded more carefully.
Absolutely pure water is almost unknown. Rain water collected in open
countries is the purest, though even it takes up matters in its passage
through the air, and in towns may be strongly acid. All waters which
have been in contact with the soil dissolve out of it numerous inorganic
and organic substances. Waters are described as hard or soft, hardness
being the popular expression for the property of not easily forming a
lather with soap. It is due to the presence of salts of lime and
magnesia. Hard waters, if their hardness be not excessive, are agreeable
and wholesome for drinking, but not well adapted for laundry or bathing
purposes. They tend to harden vegetables cooked in them, and do not make
as good tea as soft water. Rain water is, of course, the softest, but as
a rule lakes yield waters also quite soft. When a good and wholesome
water cannot be obtained from springs or rivers, as in malarial
districts, and when there is reasonable ground for thinking the ordinary
sources are contaminated by epidemics, it is well to fall back on the
rainfall for drinking purposes, with special care that it is collected
in a cleanly manner.
Surface wells are always to be viewed with suspicion when they are in
the vicinity of stables and cesspools, farm yards, cemeteries and
anywhere in the towns. The filtration of the water through the soil
removes the suspended matters, so that it may be clear enough to the
eye, but it has no power to remove impurities actually dissolved. The
eye cannot be trusted to judge the impurities of drinking water. Water
which appears absolutely clear may be unwholesome in the extreme, and
water with sediment floating in it may be in no way unwholesome. Nothing
but an analysis of the water can settle this with absolute certainty.
Deep wells and artesian wells which penetrate the surface strata are
likely to be safe. Marsh waters carry malaria and should never be drunk
without boiling. Indeed suspicious water of all sorts may be made safe
by boiling, although it is not sufficient always merely to bring it to a
boil. Thirty minutes above the boiling point is a safe rule to follow.
Typhoid, diphtheria, dysentery, cholera, diarrhea and other dangerous
diseases are caused by impure water, either by suspended mineral matters
acting as irritants, by suspended vegetable and animal matters, or by
dissolved animal impurities. Sewer gases dissolved in water, in addition
to these diseases, cause sore throats, boils and other ailments.
It must not be forgotten that water closets, stable yards, manure piles,
decaying kitchen slops and all sorts of filth are responsible for many
of the most serious diseases, either by draining into the well and so
contaminating the water supply, or by direct breeding of disease germs
carried as dust and inhaled. Health is one of the rewards for household
cleanliness of the most careful kind.