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PART IV.

WATER SUPPLY.

Importance of Water.—Water being a prime necessity of life, a universal diluent, an agent of cleanliness, its supply and quality become objects of supreme importance to the comfort and health of man. An insufficient supply leads to impurities, and the latter to disease. Any community will be sickly where water is scarce and impure.

Water Impurities.—Mineral matter in water, if excessive, renders it hurtful. Decomposed vegetable matter is a source of dangerous impurity. But the most dangerous impurity is excremental matter from animals and diseased persons, and the sewage and refuse from towns and factories. These infect entire rivers upon which cities depend for their water supply, and often breed typhoid and other epidemics. So insidious is this kind of water infection, that it is almost impossible to correct it by sedimentation, or even by filtration, unless great expense is incurred.

Quantity of Water Required.—Just how much water a household requires in a day is an open problem. More is required in cities than in rural districts for each individual of a family. Waste is also greater in the city than in the country. It is estimated that in the city a comfortable supply of water for domestic purposes would reach twelve gallons per day for each person. This embraces the amount necessary for drinking, cooking, washing of person and clothes and the house utensils. Double that quantity would be required if the water for baths and water-closets be considered.

Average of Water Required.—A healthy adult requires, on an average, about half an ounce of water daily for every pound of weight of the body. One-third of this weight is contained in the foods taken. The rest must be supplied by drinking of tea, coffee or water itself. This quantity varies according to age, sex, weight, temperature and occupation.

Sources of Water.—Rain is the great source of water. It feeds springs and rivers, cisterns and reservoirs. If carefully collected in the open country it is the purest of waters, yet at times is far from being pure, for if the air through which it descends be loaded with gases, acids and salts, as is frequently the case near cities, rain water is sure to be infected. So rain water collected in cisterns may be befouled by soot, bird excrement, leaves, dust and other impurities washed from the roof.

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Ice and Snow Water.—These waters, especially the latter, are largely used for drinking purposes. Freezing has a purifying effect on water, but when impurity is rife in water it defies the purifying process of freezing and enters the ice to make it a dangerous source of disease. Snow water is not, as a rule, considered wholesome on account of the carbonic acid it usually contains.

Spring and Well Waters.—Rain water, in passing underground, is liable to become vitiated by the character of the soils it passes through. It may in its course suspend vegetable, mineral or animal matter, gases of various kind, solid matter like lime, magnesia, iron, and so forth. Water which percolates through hard rock formations is generally pure. Granite, trap, slate, and hard grit waters are generally pure. Sand and gravel waters are variable, some being very pure, others not so. Chalk waters are generally pure, but hard. They may be improved by boiling. The same may be said of limestone waters.

Surface Waters.—These, as a rule, are impure, and yet many marshes, like those of the Dismal Swamp and the Cedar Swamps of New Jersey, contain very pure water.

Temperature and Quality of Water.—The quality of water is influenced more by the strata through which it passes than by the depth of the spring or well; but depth influences the temperature of water, for the temperature of water of shallow springs or wells varies with that of the atmosphere, while that at greater depth maintains the temperature of the locality all the year round.

Spring Water.—Spring water is commonly depended on in the country for ordinary purposes. Though spring water, especially when drawn from deep sources, is usually considered pure it should nevertheless be tested, since mere depth is not always a guarantee against impurities.

Well Water.—The well is another common source of water supply in the country. It is not as safe a water as that from the spring for it has not the same free and constant flow and it is therefore more exposed to the danger of contamination. Tests should be applied to well waters at least once a year, especially if the surrounding soils be porous, or privies or cesspools be contiguous. The deeper the well the less danger there is from impurities by percolation.

Roof Waters.—In some sections the cistern is depended on for water. In such cases the roofs and spoutings should be well looked to. Roofs, through their materials or through the use of paint, often seriously affect the quality of rain water. Spoutings also may render water impure either through the lead used in their construction or by becoming clogged. The cisterns themselves should be often cleansed, for no matter how pure the water may be with which they are fed there is no circulation in them and consequently always an injurious accumulation of sediment at their bottoms.

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Artesian Wells.—These, from their great depth and constant flow, furnish the most wholesome water supply obtainable. They are made by boring into the ground to a great depth until a layer of water is reached, which is retained beneath an impervious stratum under pressure. When this stratum is penetrated the water rises to the surface, sometimes with great force. Water from such a source will naturally be free from impurities resulting from the decay of animal or vegetable matter.

River Water.—Water of rivers and streams is a common source of supply, especially for cities or towns. River waters vary in their compositions according to the variety of their sources. They are, as a rule, softer than spring or well waters, but are often contaminated with liquid and solid refuse of various kinds due in too many instances to sewage. Though water tends to purify itself in flowing a distance of several miles, no great confidence can be placed in this process of purification of water known to be seriously polluted. The only safe course is to prevent the pollution or abandon the source of supply.

Quality of Water.—It is very difficult to define a wholesome water, but the general characters that such a water should possess are easily enumerated. They are perfect clearness; absence of color; freedom from odor and from taste (that is to say, neither salt nor sweet), good aëration; freedom from deposit on standing, and a moderate degree of softness. But a water may have all these characters and yet be unfit to drink on account of the presence of dissolved matters which it is not possible to detect except by chemical analysis.

Palatableness of Water.—A water may be palatable and at the same time be unwholesome. The following table will serve to illustrate this fact:

 

WHOLESOME 1. Spring-water VERY PALATABLE.
2. Deep well-water
3. Upland surface-water MODERATELY PALATABLE.
SUSPICIOUS 4. Stored rain-water
5. Surface-water from cultivated land PALATABLE.
DANGEROUS 6. River-water to which sewage gains access
7. Shallow well-water

 

Hardness of Water.—Water is spoken of as being hard or soft. The hardness of a water is generally due to the presence of the compounds of lime or magnesia. Hard water gives a peculiar sensation of roughness when the fingers are moistened with it and rubbed together and it does not easily make lather with soap. Soft water feels smooth to the touch and readily dissolves soap. If ordinary soap be added to hard water the mineral salts in the water decompose the soap and form insoluble compounds, which give to the water its curly appearance. Hard waters are supposed to irritate the stomach, and when they contain an excess of calcium and magnesia sulphates, may cause irritation of the bowels and produce diarrhoea in persons accustomed to soft waters. Gravel and stone in the bladder have been attributed to the use of hard water; and so also have swellings of the glands of the neck, as goitre, for example, when the hardness is due to the presence of magnesia salts.

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Boiled Water.—Boiling reduces the hardness of water and helps to deprive it of other forms of impurity. It is a good plan to boil water wherever there is a suspicion of impurity. The flat taste of boiled water may be relieved by pouring the water from a height from one vessel into another.

Pollution of Wells.—The water supply of rural and suburban districts is constantly liable to pollution from all sorts of impurities coming from dwellings. The most frequent and dangerous source of contamination is the cesspool or privy-pit. People seem to forget that the property of the soil that permits them to conveniently get rid of liquid excreta, house and waste water is that which enables the rain to supply their wells with water; and when a cesspool is placed near a well its liquid contents may reach the well through the same channels that the rain does.

The Cesspool Nuisance.—To prevent contamination of the water-supply the leaking cesspool should be abandoned and some form of dry removal substituted in its place. Earth-closets or water-tight tubs or boxes for solid and liquid excreta will answer the purpose provided they are properly made and adjusted, and frequently removed. The wells should be protected from soakage from the surrounding soil by a proper lining of impervious material. Shallow wells are always, more or less liable to pollution; and should be abandoned wherever practicable and the deep well or driven well substituted.

Polluted Water and Disease.—Diarrhoea, typhoid, cholera and kindred diseases are very frequently traceable to polluted waters. For a full explanation of this subject see the article in Book III., on "Water in its Relations to Health."

Tests for Water.—Regular chemical tests of water are, of course, the best, but the following may be applied without a knowledge of chemistry: If chlorine is present in considerable quantity it is due to impregnation of sea-water or to strata containing chloride of sodium or calcium, or to an admixture of liquid excrement of men or animals. If not due to the first-mentioned sources its presence should give rise to suspicion of sewage impregnation. If a few drops of a solution of nitrate of silver containing a little nitric acid be added to the suspected water a slight haze will be produced if only a little chlorine is present; but if there is much a marked turbidity will result which will change to a lead color. A solution of permanganate of potassium may be used to determine the presence of organic matter. If a few drops of such a solution is added to the water it produces a pinkish color which should remain sometime if the water is reasonably pure. If the color rapidly disappears it indicates excess of organic impurity, probably animal organic matter. Nichols mentions a test for sewage contamination, proposed by Heisch, which is as follows: "Place some of the water—say half a pint—into a clean, colorless glass-stoppered bottle, add a few grains of white sugar, shake until the sugar has dissolved and leave the bottle freely exposed to the light in a warm room for a week or ten days. If the water becomes turbid it is open to suspicion of sewage contamination; if it remains clear it is probably safe."

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Other Tests.—Some information of the quality of a water may be obtained from an examination of its physical characters. Its smell, taste, color and transparency will give some indications of the quality. A good water should be perfectly clear and contain no suspended matter or sediment. It should be colorless and free from odor or taste. It should be bright and sparkling, showing that it is well aerated; and it should have a certain degree of softness, so that cooking operations can be properly performed. It should be remarked that a water may possess all these qualities and yet not be free from danger. On the other hand it may be said that if all these qualities be present in a water, the chances are greatly in favor of the water being pure and wholesome.

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Last Modified: Monday, 13-May-2013 15:31:47 EDT