The well itself must be so constructed that impurities can not get into
it from above or from the sides. If water can soak into it after passing
through a few feet of soil only, it can not be regarded as secure from
pollution. To prevent this, the well may be provided with a water-tight
wall built of hard-burned brick and cement down to the water level. The
outside surface of this wall should be covered with a thin layer of
cement, and clay pounded and puddled in around it. Or, tile may be used
to line the well and the joints made water-tight with cement down to the
water level. Driven wells, i. e., wells constructed of iron tubing driven
into the ground, are, perhaps, the safest where the quantity of water
needed is not large and where other conditions are favorable.
These different devices are all designed to keep water near the surface
of the soil from percolating into the well. To keep impurities from
entering the well directly from the top considerable care is necessary.
Such impurities are likely to prove the most dangerous because there is
no earth niter to hold them back and destroy them before they can reach
the water. Adequate protection above may be provided in several ways.
The sides of the tiled wells should project above the surface and be
securely covered with a water-tight lid. The ordinary well should also
have its sides project above the surface and a water-tight cover of heavy
planks provided, which should not be disturbed excepting for repairing or
cleansing the well. Under no circumstances should objects be let down into
the well to cool. A still better method of protecting the water from above
is to have the lining wall of the well end 3 feet below the surface of the
ground and to be topped there with a vaulted roof, closed in the center
with a removable iron or stone plate. The top should be covered with 12
inches of clay or loam; above this there should be a layer of sand, and
lastly a pavement sloping away in all directions.
Too much care can not be bestowed upon the household well. It should
be guarded jealously and all means applied to put the water above any
suspicion of being impure. This is especially true in dairies where well
water is used in cleaning the milk cans, and where steam and boiling water
have not yet found their way for this end. Polluted wells in such houses
not only endanger the health of the inmates but that of a more or less
numerous body of city customers.
In those regions where rain water is the only safe drinking water, the
same care is necessary to protect the stored supply from contamination,
and no suggestions beyond those already given are necessary here.