A Handbook of Health

by Woods Hutchinson

Risks from Leaf Mould. Practically the whole surface of the earth is covered with some form of vegetation—grass, trees, or other green plants. These dying down and decaying year after year, form a layer of vegetable mould such as you can readily scratch up on the surface of the ground in a forest or old meadow; this is known as leaf mould, or humus. As the water soaks through this mould, it becomes loaded with decaying vegetable matter, which it carries with it down into the soil. Most of this, fortunately, is comparatively harmless to the human digestion. But some of this vegetable matter, such as we find in the water from bogs or swamps, or even heavy forests, will sometimes upset the digestion; hence, the natural dislike that we have for water with a marshy, or "weedy," taste.

NATURE'S FILTER-BED

The spring water is pure; the brook may gather infection as it goes.

Nature's Filter-Bed. When, however, this peaty water soaks on down through the grass, roots, and leaf mold, into the soil, it comes in contact with Nature's great filter-bed—the second place in the circuit where the water is again made perfectly pure. This filter-bed consists of a layer of more or less spongy, porous soil, or earth, swarming with millions of tiny vegetable germs known as bacteria. These eagerly pick out all the decaying vegetable substances of the water and feed upon them, changing them into harmless carbon dioxid water, and small amounts of ammonia. Not only will this filter-bed, or spongy mat of bacteria, burn up and remove all traces of vegetable decay, but if the rain happens to have soaked through the decaying body of a bird or animal or insect, the bacteria will just as eagerly feed upon these animal substances and change them into harmless gases and salts.[13]

By the time the rain water has reached the deeper layers of the soil, it is again perfectly pure and has also, in seeping through the soil, picked up certain mineral salts (such as calcium, sodium, and magnesium) which are of use in the body; so that in an open or thinly settled country, the water in streams, rivers, and lakes is usually fairly pure and quite wholesome. That is why, in ancient times, the great majority of villages and towns and camps were situated on the bank of some stream, where a supply of water could easily be obtained.

CAUSES AND DANGERS OF POLLUTED WATER

Wells—the Oldest Method of Supplying Water. It was long ago discovered that, by digging pits or holes in the ground, the rain water, in its steady flow toward the streams and lakes, could be caught or trapped, and that if the pit were made deep enough, a sufficient amount would accumulate during the winter or spring to last well on into the summer, unless the season were unusually dry. These pits, or water traps, are our familiar wells, from which most of our water supply, except in the large cities, is still taken. These wells were naturally dug, or sunk, as near as might be to the house, so as to shorten the distance that the water had to be carried; and from this arose their chief and greatest source of danger.

The Danger to Wells from Household Waste. Every house has, like our bodies, a certain amount of waste, which must be got rid of. Some of this material can, of course, be fed to pigs and chickens, and in that way disposed of. But the simplest and easiest thing to do with the watery parts of the household waste is to take them to the back door and throw them out on the ground, while table-scraps and other garbage are thrown into the long grass, or bushes—a method which is still, unfortunately, pursued in a great many houses in the country and the suburbs of towns. If the area over which they are thrown is large enough, and particularly if the soil is porous and well covered with vegetation, nature's filter-bed—the soil, the bacteria, and the roots of the grass and other plants combined—will purify a surprising amount of waste; but there is always the danger, particularly in the wet weather of spring and of late fall, that the soil will become charged with more of these waste matters than the bacteria can destroy, and that these waste poisons will be washed down in the rain water right into the pit, or trap, which has been dug for it—the well.