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The Evolution of the Conservation Movement, 1850-1920
Conservation by sanitation; disposal of waste (including a laboratory guide for sanitary engineers) by Ellen H. RichardsA. Standards of Purity. B. The Water Assay; the Engineer's Laboratory
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Does it pay to spend a city's tax money for water of a known and maintained standard? Is it a city's duty? Why not allow the purchase of water as of clothing at risk? For one reason, because the city treasury suffers in an epidemic, and the community suffers many times more, making the cost greater than prevention. But there may not be an epidemic. So in the case of a water too hard or too corrosive, why not allow each manufacturer to use whatever rectifier he chooses and not compel him to pay for a municipal water-softening plant? He may be a dangerous neighbor if his boiler blows up. It will cost the city more for inspection and for damages.
All this amounts to but one thing. The modern city must pay for assurance against loss of life or of efficiency and consequent financial loss. It might actually take out an insurance policy of a few million dollars against loss by a typhoid-fever epidemic, let us say. This would be good economics, but there is a still better form of assurance. This is protection against epidemics--pure city water for instance. Banks have found the Bankers' Protective Association a decidedly profitable investment. The village, town, or city hesitating between two grades of water must settle the problem by pure economic reasoning. They must figure the risk from the use of each just as the fire-insurance agent would figure his risk on the town hall. The better supply is of course the least risk, but possibly the premium required to install and operate the plant
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is more than it would be good economy to pay. The premium to be paid in each case must be determined from the reciprocal of the risk rather than from the actual risk itself. That is, the less the risk of infection from a certain source the greater the premium that it is permissible to pay to obtain that source, and vice versa.
In figuring the risk from any given source of supply, everything affecting the possible economic loss to the city should be considered, not only fatal epidemics but minor epidemics, slight infections resulting in bowel and stomach disorders, causing temporary disability or loss of efficiency in the community's workers, injury to machinery or manufactures from the mineral contents of the water, and possibly the lessening of residential desirability of the town, by color, tastes, or odors in the water. All these depend on the quality of the water. The quantity should of course be figured on taking into consideration the possible loss engendered by lack of water for fire control or for industrial establishments, etc.
Of course the figuring of such risks and the resultant economically correct premium is going to be by no means an easy task, yet it is surely possible and it is obviously practical. The adoption of such a conception of insurance as the guiding economic principle of community sanitation would not only mean more money, but more money more freely and more understandingly given, or rather invested, by the taxpayer, as well as a much higher standard of efficiency in the various departments of control.
As the actual cost of sickness is being estimated on a higher basis the economy of even larger expenditure is seen.
The engineer to-day who says, "Pure water is the people's right," is right as far as he goes. He doesn't say whose right it is to pay for it, however, and that is just where the rub comes to-day in our big cities. The people all want pure water, but they are a long way from all wanting to pay for it. They must be convinced, in most cases, that by paying for it they are actually insuring themselves against actual financial loss,
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before they will vote for a larger issue of water bonds to raise the standard of quality of the water in the mains. The sanitarian is all too prone to harp on the humanitarian side of municipal improvements. In the tangled, many times compounded Babel of American citizenship of the twentieth century there is only one tongue that is universally understood, and that is that of money.
Before the value of an article is set, there must be some method of comparison between different qualities, and in a consideration of a water supply standards of purity have been sought as a basis for decisions as to sources, treatment, extension of works, and many other details.
A naturally treated ground water from spring or driven wells should be clear, cold, colorless, containing no ammonia, no nitrites, no suspended matter, therefore no bacteria, no dissolved organic matter.
It may contain dissolved mineral substances even up to 1000 parts per million without rendering it unpotable.
It will probably contain 20 to 50 parts even if derived from the early Archean horizon with glacier ground soil.
The decision as to its past history depends on the variation of the mineral contents from the normal of the region. Excess of chlorine and nitrates can come only from pollution of some sort, up to the sewage limit of chlorine; beyond that it is probably contaminated by sea water.
In eastern North America excess of sodium salts also indicates contamination, while the reverse is the case in the arid and semi-arid regions. The history of a water must be known by the engineer before the recommends its use.
Natural untreated water is that deposited from rain collected in streams finding its way from high collecting ground to the ocean by open chambers, now and then detained by resting places, as lakes and sluggish reaches.
Standards of purity for such waters naturally vary from those for ground treated water.
For such waters the above list of characters, clear, cold,
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colorless, odorless, sparkling, is replaced by the single requirement "free from pathogenic germs." The water may be thick with mud, brown as coffee, smell of fish, oil or cucumber, taste as flat as distilled water, and be as warm as the air, and it is taken in a contented spirit if it is pronounced "safe"; that is, sanitary cranks take it. Conservative persons fail to see the reason for change of ideal, and therefore typhoid fever continues to be spread by country wells and imperfectly purified rivers.
Water is the great carrier and solvent and will extract something from each obstacle in its flow. If it encounters a jam of logs, a pile of sawdust, a dead deer or fox, a barnyard or chicken farm, a paper mill, a village, each will leave its mark. He who knows will read.
Surface water as a rule should not have more than the normal chlorine, more than .200 nitrates, or more than .010 free ammonia.
The allowable albuminoid ammonia depends on the color derived from the humus, peat, leaves, etc. Other characteristics, as turbidity, vary with each shower.
Artificially treated water is brought as near to the ideal clear, colorless, odorless standard as is possible. It is brought down to a certain minimum of bacteria to lessen the risk. This is a purely arbitrary standard, a workable rule.
All artificial filters are hurry processes and only approximate the slow, natural ones in giving quality.
The chief purpose of a filter plant is insurance to lessen the risk. Ęsthetic considerations usually come second; hence the substances that are without sanitary significance are often neglected. Color is one of these. The removal of dangerous bacteria may be accomplished without taking the color, because the sand filter is made of washed sand, the clay is removed, and the rate is very rapid as compared with natural ground filter. But it is possible to remove color as well as bacteria by the addition of chemicals. However, the standards for treated waters are yet uncertain. The waters themselves are receiving
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ever new varieties of materials, new combinations, and there is a shorter and yet shorter time between contamination and use. What effect these "repentant waters" have on the human system, whether there remains some subtile tendency, some unrecognized product from the action of the nitrifying organism, from the processes of conversion of the organic to the inorganic, is not known.
Nature's processes are always time processes and the healing power of time, whether for sorrow or disease or recovery of water, is the largest element. Certain it is that the quick processes to make polluted water as "good as new" have failed like such claims in other directions. No evidence has yet accumulated to show that well-filtered stored water retains harmful qualities.
Numerical standards, as well as the substances chosen to be indicative, have varied with the varying theories of the causes of danger in use of the water. At the time when "organic matter" was held to be the dangerous substance the amount of oxygen absorbed was not to exceed 0.500 part per million. 2.100 parts indicated impure water.
With the advent of the albuminoid ammonia theory, Wanklyn set 0.150 part of ammonia in a million as the allowable limit. When the bacterial count became the criterion 100 per cc. was a favorite figure.
Putrescible organic matter is of course to be removed, but sterile, soluble organic matter may be food for yet other organisms farther on. The only safety is, therefore, to use such water at once. For mechanical filters the standard has been the bacterial count given above, trusting that the human sterilizing fluids will take care of the few that escape. 100 per cc. may be far too many to allow, but for every ten less the cost is increased perhaps one-tenth, and until experts can prove this further reduction to be necessary, the standards permitted will not be more rigid.
All filtered waters should keep clear and bright with no development of bacteria for twelve hours. For setting the
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standard of the water the count at the instant of leaving the filter is of less moment than the count ten to twelve hours after.
The physical efficiency, or as we choose to call it, the economic efficiency, has very frequently little to do with the sanitary efficiency.
Physical and chemical standards will depend largely on the character of the water in each case. 99 per cent of suspended matter should be removed. Color follows in mechanical filters, but soluble substances except calcium sulphate and carbonate are not retained. Chlorine and to a considerable extent ammonia and nitrates are found intact in the effluent.
Cost is a limiting factor in modern standards. In the case of grade crossings, it was cheaper to pay for a few people killed than to raise the tracks. So in water supplies, it was cheaper to advice the boiling of the few gallons of water for drinking than to provide two hundred gallons a day of safe water for all uses.
In ancient times the wholesomeness of the supply was determined by animal experimentation, that is, survival of the people using it.
Epidemics became more frequent with increase of population, until authorities began to ask if there was a scientific basis for assuming that there was real economy in spending money to purify the water supply.
To-day the greater responsibility of the State for the care of its citizens and the greater estimate of the value of human life have shown the real basis of this economy.
The progress of the science at the basis of furnishing a satisfactory water supply is best illustrated by a few quotations.
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