HOW DISEASE GERMS GET INTO WATER
The water that we drink frequently contains disease germs. It is
not always the clearest water that is freest from disease germs,
for the germs do not make the water cloudy.
[Illustration: FIG. 45. An improperly located well; notice lines of
seepage.]
[Sidenote: Why sewage should not be put into streams]
Water does not get disease germs from the ground, but from man.
Almost every town has a sewer system that empties into some stream.
This practice was started a long time ago when men thought that
running water would purify itself in the course of a few miles. We
have learned, however, that this is not true. Germs will continue
to live in running water just as they do in any other water, and
disease germs will live in a stream from twenty-five to thirty-five
days. Estimate how far a stream will flow in that length of time,
and you will know how far disease germs will travel in that way. No
sewage should ever be allowed to get into a stream until the germs
in the sewage have been killed.
[Sidenote: Other sources of germs in streams]
Sewage is not the only means by which disease germs are carried
into streams. Often we find people building barns, slaughterhouses,
and mills on the banks of a stream. The filth from barns and
slaughterhouses always contains disease germs, and often the filth
of mills contains poisons that are just as harmful as germs when
taken into our bodies. None of these things should ever be allowed
to get into a stream. Water is a very important article of food,
and we should take every care to keep it pure.
[Illustration: FIG. 46. A properly located well.]
[Sidenote: How germs get into wells]
The water from most wells is clear and cool, but nevertheless
may contain many disease germs. "How does this happen?" you ask.
Because the well is too close to an out-house or some other source
of filth. When a man in the country or in a small town builds a
house, he immediately thinks of digging a well just as close to the
house as he can, so that he need not carry the water far. Next he
thinks of locating the closet, and this, too, he wants near the
house. The well and the closet are often near each other, and often
the closet is on higher ground than the well. The vault under the
closet is seldom water-tight. In fact, the intention of the owner
is that a great part of the vault contents shall soak away.
In many localities the ground is an open gravel, and the vault
contents run through this gravel into the well, carrying disease
germs with them. In one little town, with wells as a source of
drinking water, the health officers found that the closet of every
house was draining directly into its well. In some countries vaults
can be used; but in any region where there is a gravel subsoil, the
contents of the closet will find their way into the well, unless
the closet is lower than the bottom of the well. In such places the
vault must be made water-tight, in order to keep the vault contents
out of the well.[2]
[Sidenote: Why springs are not always pure]
Springs are usually sources of pure water, but do not think that
every particle of water that oozes from the ground is a spring.
Near a certain town is a so-called "very fine spring." This
"spring" appeared after a man had made a cesspool on the hill
above, and is simply the drainage from the cesspool. Springs that
come from deep sources, however, nearly always contain pure water.
[Sidenote: The safest sources of water]
The safest source of water for domestic use is a stream that is
known to be free from contamination, or a well so deep in the
ground that it is hard for any polluting matter to reach it. But
remember that sewage may follow a well pipe along the outside and
thus reach even a deep well, if the well is not properly protected
at the top.
Keep disease germs out of your drinking water. You cannot drown
them out and you cannot strain them out, so do not let them get in,
for you cannot drink water containing disease germs without running
the risk of becoming sick.
=Questions.= 1. Mention more than one way in which germs get into
streams. 2. How long may disease germs live in running water?
3. Mention some instances showing that running water does not
purify itself. 4. How do disease germs get into milk? 5. Describe
the proper location of a well in regard to refuse. 6. How may
springs become polluted? 7. What are the best sources of water
for domestic use?
=Remember.= 1. Disease germs get into water from dirty places
along the banks of the streams; they do not come from the ground.
2. Clear water is not always pure; germs do not make the water
cloudy or muddy. 3. Wells often become infected by matter from
closets seeping into them; make your closet water-tight. 4.
Spring water is usually pure, but not all water that oozes out of
the ground is spring water.