POTABLE WATER

BY

PROFESSOR FLOYD DAVIS, M. Sc., PH. D.,

CHEMIST OF IOWA STATE BOARD OF HEALTH.

“He who learns the rules of wisdom without conforming to them in his life,

is like a man who labored in his fields but did not sow."-SAADI.

Appendix-Potable Water.

POTABLE WATER.

I. PURE WATER.

Water is a chemical compound of hydrogen and oxygen, which is widely diffused in nature. As a solid, it exists as snow and ice; as a liquid, it constitutes streams, lakes and seas, and in a state of minute subdivision, mist and clouds; while as a colorless gas, it is always a constituent of the air. Natural waters are always impregnated with certain foreign constituents which give to them their varying properties; and in the examination of water for sanitary purposes, it is not the water which is analyzed, but its impurities.

The palatability of water depends upon its occluded gases, which are principally oxygen, nitrogen, carbonic anhydride and hydrogen sulphide. These gases are readily absorbed, and they give to the water an agreeable taste, and a sparkling brilliancy. The high degree of palatability of spring-water is mainly due to its carbonic anhydride. Distilled water, or water deprived of its gases by boiling, is insipid or "flat;" but by aeration and acidification it regains its palatability. Water must be more or less impregnated with gases before it is even suitable to the dietetic needs of man; for when water deprived of its gases, is used for purposes of experiment, it is found to be prejudicial to health, as the stomach cannot gratefully receive and advantageously appropriate it. (')

Researches in etiology have shown that the health of an individual, or of a community, depends largely upon the purity of the water supply. It is not chemically pure water, however, that is needed for the maintenance of perfect health, for such water does not exist in nature. As chemically pure water contains nothing injurious to the system, it likewise contains nothing beneficial, and for healthy persons, such water is not the most wholesome. The

(1) Van Nostrand's Engineering Magazine, December, 1872, p. 593.

Appendix-Potable Water.

healthy human system ordinarily requires mild cathartics and other mineral salts for the continuity of health. These, in part, can be best furnished to the system as the mineral constituents of potable water. The wholesomeness of water is therefore increased by the presence of small quantities of certain mineral salts, in solution, which act as laxatives, and which are essential to the development of animal tissue; but drinking water should be free from organic impurities. As a rule, chemists condemn all waters which are contaminated with sewage, such contamination being shown by chemical and microscopical analyses, and by an examination of the sources of supply. From a sanitary standpoint, pure water may be defined as water which is unobjectionable for general domestic use, and especially that which may be used with perfect safety for drinking purposes.

Some waters are so unpotable that the appetite does not demand the amount required for the normal functions of the body. Such waters not only lessen bodily vigor and frequently produce disease, but an insufficient supply of any water is manifested by great pain, relaxation of muscular strength and of mental vigor, and diminution in the elimination of pulmonary carbonic anhydride and bodily excretions. So, when we consider that about seventy(") per cent of the human body is composed of water, which is being constantly eliminated, the need of maintaining a copious supply of pure water becomes apparent; but an abundance of water is no more necessary to the support of life than its purity is to the continuity of health. People may habitually drink impure water and still live, but its use unquestionably affects the human frame and tends to the degeneration of a race. Experience shows that even slightly impure water may be productive of a host of ailments for which the sufferer finds no apparent cause; for the results are often so slow and gradual as to evade ordinary observation, and the evil is borne with the indifference and apathy of custom. It is only when striking and violent effects are produced that public attention is arrested.

A water which is constantly used for domestic purposes should have the following qualities:

(2) Human Physiology, Seventh Edition, Dalton, p. 36.

Appendix Potable Water.

1st. It should be free from odor and taste.

2d. It should be free from dead vegetable and animal organisms, and should contain only such living forms as are purifying agents.

3d. It should at all seasons of the year be well aerated, uniform in temperature, and free from suspended matter.

4th. It should contain only a small quantity of mineral matter in solution, and be free from all the poisonous salts.

For persons afflicted with renal diseases, distilled water in its crystalline purity is probably the most healthy beverage, for it acts upon the kidneys as a powerful therapeutic agent in the solution and removal of the waste products of the body. Upon this point Professor Charles Mayr() says: "Those who have never drunk pure water do not realize what an effect such water has upon the kidneys; its effect is better than that of acetates, nitrates, opiates or alcohol, and for people with tendency to kidney diseases or Dropsy there is no better drug than pure water. Of the thousands of chemical compounds and waste products found in the human system, many require pure water for their solution and elimination; and water so overloaded with salts as average well-water will not work satisfactorily."

II. INORGANIC IMPURITIES.

Water is the most nearly universal solvent in nature, and as it passes into the earth, charged with atmospheric gases, it dissolves many salts. When it reappears again on the surface in springs, and flows away in streams, it is often heavy laden with mineral constituents; but the streams and lakes in granite regions are very nearly pure. The oceans and inland seas are the final reservoirs of flowing water, and they become saline from the concentration of their mineral matter, through evaporation. Sea water contains about two thousand grains of total solids per gallon, while the waters of the Great Salt Lake and the Dead Sea each contain about twelve thousand grains. (*).

(3) Report of New Jersey State Board of Health, 1887, p. 338. (4) Manual of Mineralogy and Petrography, Dana, p. 252.