Mechanics of the Household / A Course of Study Devoted to Domestic Machinery and Household Mechanical Appliances

by E. S. Keene

Fig. 123.—Some of the common causes of pollution of wells, and the means of transmitting disease, such as typhoid, etc.

Pollution of Wells.

—The water from wells is often polluted by seepage through the earth from sources that might be prevented. Fig. 123 illustrates some of the commonest sources of contamination that through carelessness or ignorance are located in the neighborhood of the family water supply. The drainage from such sources of pollution is often directed toward the well and many cases of ill-health, disease or death are the direct consequences of drinking its water. It may be readily observed, in the case of the well illustrated, that the more water that is pumped from the well, the greater will be the tendency of the water from each of the sources of pollution to reach the well.

Another common cause of contamination of well water is that of imperfect well curbs that allow the waste water or surface water to flow into the well. The area about the well should be graded to allow no standing water, and the waste should be conducted away without permitting it to collect in standing pools.

Drainage from manured fields or other places where disintegrating animal or vegetable matter may be absorbed by water is often the cause of temporary pollution, where the water is carried to low-lying wells. Wells located in low areas that receive the drainage from such places may be suspected of pollution during the spring or early summer, when during the remainder of the year the water is pure.

In connection with any water suspected of pollution, it is well to remember that by boiling the water used for drinking, its harmful properties are entirely destroyed.

Safe Distance in the Location of Wells.

—In the location of a well, the distance of safety from sources of pollution will depend, in a considerable measure, on the character of the soil and the quantity and concentration of the pollution material entering the ground water. When coming from the surface, the danger is usually neither great nor difficult to avoid; but when cesspools and privies in the neighborhood are sunk to a considerable depth in porous earth, from which the supply of water is drawn, the polluting material may reach the well undiluted. No absolute radius of safety can be given, but certain generalizations as to conditions may be made as to character of soil and the different topographical conditions which surround a safe location.

In ordinary clay, or in clay mixed with pebbles and in soils of the same general nature, through which the water circulates by seepage, the pollution is not likely to be carried to a distance of 100 feet. Clay offers marked resistance to the passage of water, which in beds of 3 to 5 feet thick will act as protection from pollution from above. In sandy soils the movement of water is faster than in clayey soils, but 150 feet may be taken as a safe distance, unless the downward slope of the land carries the polluting material directly to the well.