Water is the great natural diluter. From three fifths to four fifths of the bodies of plant and animal life are made up of water. It is more necessary to life, especially higher life, than more nutritive material. Human beings can survive weeks without food but only days without water.
Yet even pure water, when viewed under compound microscopes, is almost never free from microbes. Even rainwater, coming as it does through a dusty and sooty atmosphere, cannot be pure chemically or bacteriological. Water from deep wells and springs, on the other hand, is usually fairly free from pathogenic microbes. Or it should be free, at least, from bacterial pathogens. Unfortunately, through man’s carelessness or ignorance, animal and human refuse is frequently allowed to contaminate even deep wells and springs.
Shallow wells, streams, ponds, and lakes, as well as sea waters, all contain microbes when examined under compound microscopes, many of them pathogens, resulting from human and animal excreta washed into them by rains and sewers. We find microbes, mostly saprophytes and protozoa, even in hot springs. These are the thermophils. The Great Salt Lake in Utah, despite the concentrated saltiness of its waters, supports some microbial life. The will-o’-the-wisp of marshlands and the sea phosphorescences are microbial products. The Great Lakes, the Missouri-Mississippi system, the Hudson and other rivers in the greater New York area, all contain water not only unfit to drink but frequently even dangerous to bathe in; for they drain the sewage from many large population centers. The New York Department of Health repeatedly has warned the public not to bathe in the sewage-polluted waters around the city.
One of these days, some of our great cities, especially such as are as backward in installing a sanitary sewage disposal system as is New York, yet may find themselves with a serious water-borne epidemic on their hands. Perhaps just such an avoidable sacrifice of lives is the only thing to wake up the voters to the criminal negligence of some of their public servants. Most of our rivers are sewage ditches, and many a swarming bathing beach nothing but a diluted cesspool.
If we trace the matter back to its root, we find that the menace to health lurking in unprotected watersheds and wells derives from the physiologic fact that human excreta often is about nine tenths microbes. Most of these, it is true, are not bacterial pathogens, but some of them may be, and certainly those deriving from diseased persons are. Fortunately, in the United States the water-borne infections are ordinarily only typhoid fevers and the dysenteries. This does not mean, however, that other bacterial pathogens are not sometimes present in polluted drinking water. In some of the hygienically backward European and Asiatic communities the typhoid and dysenteries occasionally are reinforced by cholera, bubonic plague, typhus, etc.
There are two ways of keeping drinking water palatable and pure. The first, of course, is to see to it that its sources are not polluted. This is not so difficult where the number of consumers is small and the watershed adjacent. It can be accomplished by building sanitary wells and insuring that sinks, stables, and privies do not drain into them. Where, on the other hand, the consumers number hundreds of thousands and the water supply must be collected in distant, extensive watersheds, the problem is complicated by the necessity of using the aggregate waters of many streams, and by the presence of too much surface water from sources which cannot be well controlled. Then it is that the second method of making drinking water safe and pleasant must be used.
This second method is the filtration and chlorination of the water in the reservoirs, which store it before it enters the consumer mains. Of course, a certain amount of purification due to ultra-violet rays, sedimentation, crystallization, and compound microscope seen cannibalistic higher microbes takes place naturally. But no community having a health officer worthy of the name would rely on natural purification alone for a safe drinking water.
