"W ATER may be clear, colorless, fresh, agreeable to the taste, excellent for washing and cooking, and nevertheless, with all these admirable qualities, dangerous to drink. This danger arises from microbes in the water, though nothing betrays their presence, neither smell nor taste, nor any lack of clearness, nor the least impairment of the water for household uses. Since certain kinds of these infinitesimal organisms cause serious maladies, we imperil our health by taking them into our bodies in our drink. Water, therefore, to be good to drink, should contain no microbes. One well may furnish water of irreproachable purity, while another may be more or less infected with microbes and hence pernicious and dangerous despite all appearances to the contrary.
"Where, then, are we to look for perfectly pure water, water that we make drink without thought of danger? It is furnished only by springs. Let us dwell for a moment on the origin of springs, and we shall then understand why spring-water is pure. Rain, melting snow, the dampness of night fogs, soak into the ground, especially on mountain slopes; and the water thus absorbed over large expanses of surface sinks to a great depth, collects in little underground streamlets, makes its way through opposing soil and sand, also through the cracks in rocks, and comes to the surface again in some distant valley, welling up through a fissure and producing a spring.
"From its starting-point to its destination the water thus passes through a sort of filter of enormous thickness, kilometers thick in fact, and at a sufficient depth to be free from surface defilement. By passing through successive beds of clay, marl, sand, crumbling rock, and porous stone, the water gradually rids itself of its impurities and leaves them behind, so that on reappearing above ground it no longer contains any corpuscles even of the microscopic minuteness of microbe germs. Spring-water is pure by virtue of the thorough filtering it has undergone, a filtering such as no means at our disposal could begin to achieve.
"Can we say as much for the purity of river-water and brook-water? Far from it. These streams, especially in the neighborhood of large cities, receive frightful quantities of foul matter. Into them empty sewers charged with the refuse from streets and dwellings; in their waters are washed the garments we have soiled and the foul linen that has served as bandages for sores; their channels are choked with all sorts of decaying matter from many factories. It is therefore evident that river and brook, however clear their water, cannot furnish us with a drink that is free from suspicion. Microbes abound, and those of cholera, for example, may be among them, from the person of some victim to that disease or from the linen used in his treatment.
"Not even a country brook is void of offense. Rain-water washes the tilled fields, soaks through the manure spread as fertilizer, and carries to the stream the harmful germs that breed in all decay.
"Well-water, besides being not always sufficiently aërated, is likewise subject to defilement. In the first place, owing to its slight depth, a well becomes charged with water from the upper layers of the soil, a filter not thick enough to arrest injurious germs. In the second place, wells in towns are dug in ground that has become defiled to a considerable depth by the prolonged sojourn of man. Not far away are drains and sewers and other repositories of filth, from which it is very difficult to safeguard the wells.
"In the country the danger is less, provided the well be covered so as not to admit any dead leaves or the dust raised by the wind; and provided especially that the well be at a distance from all stables, dung-heaps, deposits of compost, and other sources of infection through infiltration.
"Mere taste and appearance make us reject for drinking-purposes all water that repels by its odor, its taste, or its lack of clearness. But this is not enough. It is now established beyond doubt that certain diseases, especially typhoid fever and cholera, are propagated by water containing their microbes. Suspicious as we must at all times be of river-water and well-water, in periods of epidemic we should exclude them entirely from our use and have recourse to spring-water alone.
"But not every one can obtain spring-water, What shall be done in such cases? The answer is simple. We have seen that the temperature of boiling water kills all living creatures. River-water or well-water can accordingly be rendered quite fit for all our uses on the express condition that it be first boiled. Freed of its noxious germs by heat, it is thenceforth harmless.
"Summing up these points in a couple of precepts of prime importance to our health, we may say: Keep all wells and springs free from filth, and when cholera is prevalent use no well-water or any water from river or brook without first boiling it."