atements.

_Definition of "Ground-water Level"_

Water percolating through the soil passes downward by gravity until it
reaches an impervious stratum. The surface of this underground sheet
of water is technically called "water table" or ground-water level.
The water is not at rest, but has a slow and well-defined motion, the
rate of which depends upon the porosity of the soil and also upon the
inclination or gradient of the water table. A shallow well may be
either excavated or driven into this subsoil sheet of water. In
populous districts, in villages, towns, but also near habitations, the
soil from which water is obtained must, of necessity, be impregnated
with organic waste matter. If, in such a surface well, the level of
the water is lowered by pumping, the zone of pollution is extended
laterally in all directions. Ordinary shallow well water should always
be considered "suspicious water." There are two distinct ways in which
surface wells are contaminated: one is by leakage from cesspools,
sewers, privies, etc.; the other, just as important and no less
dangerous, by direct contamination from the surface. The latter
danger is particularly great in wells which are open at the surface,
and from which water is drawn in buckets or pails. A pump well is
always the safer of the two. Frogs, mice, and other small animals are
apt to fall into the water; dust and dirt settle into it; the wooden
curb and the rotten cover also contribute to the pollution; even the
draw-buckets add to it by reason of being often handled with unclean
hands.

Always avoid, in the country, drinking water from farmers' wells
located near cesspools or privies. Such shallow wells are particularly
dangerous after a long-protracted drought. It is impossible to define
by measurement the distance from a cesspool or manure pit at which a
well can be located with safety, for this depends entirely upon local
circumstances. Contamination of shallow wells may, in exceptional
cases, be avoided by a proper location of the well with reference to
the existing sources of impurity. A well should always be placed
_above_ the source of pollution, using the word "above" with reference
to the direction in which the ground water flows.

_Precautions Regarding Wells_

Other precautions to be observed with reference to surface wells are
the following:

Never dig a well near places where soil contamination has taken or is
taking place. Line the sides of the well