A Handbook of Health. Woods Hutchinson
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.
Here the farmhouse is set above the barn, pens, and cattle yard, and at some distance from them. The drainage from these is into the lower fields, so that a well driven into the high ground not far from the house is presumably safe.
The Danger from Outbuildings. This danger is further increased by the fact that for the same reason—the vital need of plenty of water for all living creatures—the hen coop, the pig pen, the cow stable, and the horse barn are all likely to be built clustering around this same well. If the fertilizer from these places is, as it should be in all intelligent farming, protected from the rain so as not to have all its strength washed out of it, and removed and spread on the soil at frequent intervals, the well may even yet escape contamination; but the chances are very strongly against it. If you will figure out that a well drains the surface soil in every direction for a distance from ten to thirty times its own depth, and that the average well is about twenty-five feet deep, you can readily see what a risk of contaminating the well is caused by every barn, outhouse, or pen within from sixty to a hundred and fifty yards from its mouth.
Every well from which drinking water is taken should be at least fifty, and better, a hundred and fifty, yards away from any stable, outhouse, or barn; or set well up-hill from it, so that all drainage runs away from its basin. This, of course, is possible only in the country, or in villages or small towns, where houses have plenty of ground about them. Consequently, the health laws of most cities and states forbid the use of shallow wells for drinking purposes in cities of over 10,000 population.
Causes which Produce Pure Well Water. Occasionally a well will be driven through a layer of rock or hard water-proof clay, before the water-bearing layer of soil, or sand, is struck, so that its water will be drawn, not from the rain that falls on the surface of the ground immediately about it, but from that which has fallen somewhere at a considerable distance and filtered down through the soil. This water, on account of the many, many layers of soil through which it has filtered, and the long distance it has come, is usually fairly pure, so far as animal or vegetable impurities are concerned, though it is apt to have become too strong in certain salty and mineral substances, which give it a taste of salt, or iron, or sulphur. If, however, it is free from these salty substances, it makes a very pure and wholesome drinking water; and if the upper part of the well shaft be lined with bricks and cement, so that the surface water cannot leak into it, it may be used with safety for drinking purposes even in the heart of a city.
The milk inspector on visiting this dairy farm found that the well was receiving the drainage of both house and privy. The well water was used for drinking and for washing the milk pails (seen behind the fence).
The Greatest Single Danger to Well Water. The greatest single danger to the purity of well water is the privy vault. This is doubly dangerous, first, because it is dug below the level at which the bacteria in the soil are most abundant and active, so that they cannot attack and break up its contents; and the impurities, therefore, are gradually washed down by the rain water into the soil, unchanged, and seep directly into the well. The other reason is that its contents may contain the germs of serious diseases, particularly typhoid fever and other bowel troubles. These germs and their poisons would usually be destroyed by the bacteria of the soil, if not poured out in too large quantities; but in the privy vault they escape their attack, and so are carried on with the slow leakage of water into the well; then those who use that water are very liable to have typhoid fever and other serious diseases.
Early Methods of Prevention. On account of these filth-dangers, it began, a century or so ago, to be the custom in cleanly and thoughtful households to provide, first, ditches, and then, lines of pipes, made out of hollow wood or baked clay, and later of iron, called drains, through which all the watery parts of household wastes could be carried away and poured out at some distance from the house. Then toilets, or flush-closets, were built, and this kind of waste was carried completely away from the house, and beyond danger of contaminating the wells.
How Streams were Contaminated. For a time this seemed to end the danger, as the waste was soaked up by the soil, and eaten by its hungry bacteria and drunk up again by the roots of plants. But when ten or a dozen houses began to combine and run their drain-pipes together into a large drain called a sewer, then this could not open upon the surface of the ground, but had to be run into some stream, or brook, in order to be carried away. As cities and