Popular Science Monthly/Volume 14/November 1878/Drinking-Water from Agricultural Lands
|←Professor Tyndall Before the English Copyright Commission||Popular Science Monthly Volume 14 November 1878 (1878)
Drinking-Water from Agricultural Lands
By J. A. Judson
|Education as a Science VI→|
LITTLE as it appears to be appreciated, there is to-day no question of sanitary science of greater vital importance than that of the quality of the water-supply entering into the daily domestic economy. The requirements and refinements of modern civilization demand not only a plentiful but a profuse supply of water, and at a moderate cost—facts long ago recognized and acted upon. While enormous capital and the best engineering talent have been very generally called upon, both in this country and in Europe, to economically furnish water in ample quantity, a corresponding degree of skill and enterprise has not always been directed to the determination of its quality.
It is not impossible to point out authorities on sanitary matters so wedded to pet theories that they unhesitatingly deny that the conversion of a pure running stream, or even a large river, into a conduit for the sewage-filth of a great city, will have any deleterious effect on the potable quality of the water taken a few miles below the filth-entering point. It has been demonstrated that this is not only false in theory but also in fact. It was Dr. Letheby, of the English "Royal Commission on the Water-Supply of London," it is believed, who was the first to announce what has since been proved a fallacy, viz., that "if sewage be mixed with twenty times its volume of river-water, the organic matter which it contains will be oxidized and completely disappear while the river is flowing a dozen miles or so;" and further, that "it is safe to drink sewage-contaminated water after filtration." The "Royal Rivers Pollution Commission" of 1868, unwilling that this expression of opinion should remain untested, submitted it to careful and ingenious experimental investigation. The result is thus announced:. . . "It is thus evident that so far from sewage mixed with twenty times its volume of water being oxidized during a flow of ten or twelve miles, scarcely two-thirds of it would be so destroyed in a flow of one hundred and sixty-eight miles, at the rate of one mile per hour, or after the lapse of a week." And, after mentioning certain details in support of this, the commissioners conclude with the remark that "it will be safe to infer, however, from the above results, that there is no river in the United Kingdom long enough to effect the destruction of sewage by oxidation." Dr. Frankland, an eminent English authority, before the Royal Commission on Water-Supply, gives some strong testimony in support of the statement that it is impossible to remove the sewage contamination from water by any known process, natural or artificial, so as to render it harmless, except by boiling for a long time, or by distillation; and, as these two processes are impracticable on a large scale, then, he says, in his opinion, "water that has once been contaminated by sewage ought not afterward to be used for domestic purposes; and, inasmuch as it is generally believed that the noxious matter of sewage exists there in the form of minute germs, which are probably smaller than blood-globules, I do not believe that even filtration through a stratum of chalk could be relied upon to free the water perfectly from such germs." According to the same authority, "the noxious part in sewage is that which is held in mechanical suspension, not held in solution;" and yet, he says, and truly, "no system of filtration will secure its removal." Colonel J. W. Adams, C. E., in a valuable paper on river-pollution, follows up this subject to its logical conclusions. Dr. Folsom, in the "Report of the State Board of Health of Massachusetts for 1876," also attacks this branch of the question, remarking that "excessive dilution simply diminishes the chances of danger from any particular tumblerful." He here states a case of transmission of disease in dilute sewage, to which special attention is invited, as showing quite conclusively the fatal result ensuing from reposing too great faith in the extermination of disease-germs by oxidation, and of reducing the chances of transmitted disease by diffusion of disease-germs through a large body of running water. Dr. Folsom says: "The most striking case illustrating this law is one reported by Dr. E. D. Mapother, of Dublin. Forty cases of typhoid fever occurred in a hospital which received its supply from a river. The cause was traced to some barracks twenty-five miles higher up, from which typhoidal dejections had been emptied through drains into the river."
It would be easy to multiply authorities on this point. Suffice it to say that this pernicious theory is happily exploded, and that the Second English Rivers Pollution Commission publish conclusions, based on the examination of some two thousand samples of water claimed to be drinkable, condemning river-water because it is liable to contamination from drainage of cultivated land, towns, and manufactories. They state that "the admixture of even a small quantity of these infected discharges (of persons suffering from cholera or typhoid fever) with a large volume of drinking-water, is sufficient for the propagation of those diseases among persons using such water." The case related by Dr. Folsom, previously quoted, as well as numberless others of a similar sort, proves the accuracy of this conclusion.
The English commissioners then classify potable waters as follows, and, when we consider the high authority for this scale of wholesomeness, it would seem that it should carry great weight with it. Though often published before, it cannot be too frequently repeated:
|2. Deep-well water.|
|3. Upland surface-water.|
|4. Stored rain-water.|
|5. Surface-water from cultivated land.|
|6. River-water to which sewage gets access.|
|7. Shallow-well water.|
While wholesale river-pollution from any source is utterly inadmissible on any sanitary grounds, so infinitesimal pollution by dilute sewage, indirectly discharged into the water-course, is equally dangerous, and attended with sure though more remote fatal results, "especially if human excreta he present in any form whatever." The whole subject is intimately connected, but it is to this latter point more particularly that this paper leads, as touching the pollution of entire water-basins through the application of organic manure to their gathering-surfaces, for agricultural purposes, and the consequent pollution of the water derived therefrom.
It is well known that many years ago the pollution of the watercourses began to excite public attention in England, and the labors of the several "Rivers Pollution Commissions," and other sanitary committees organized by authority of Parliament, bear testimony in their elaborate and invaluable reports to the truth that humanity can no longer afford to ignore that foul water will breed disease. The dense population of England, and the resultant mass of concentrated filth, have there compelled attention to those laws of health that we, with our enormous area of comparatively thinly-settled country, and the consequent high dilution of foul water and foul air, have felt safe in disregarding. This feeling of safety is, however, fallacious; for, as facts attest, "filth-diseases" are as liable to break out in an isolated house as in a crowded city, if the fundamental hygienic laws are violated. The distinguished labors of the State Board of Health of Massachusetts, as well as those of various other similar boards, bring the subject home to us in a forcible manner, and the sooner we know what sort of water we are drinking the better for us and for those who succeed us.
As fair water is at once a prime necessity and a priceless blessing, so foul water is a scourge and curse; nor will any but a sewage-rectifying enthusiast hesitate for an instant which to choose, provided he has the means of knowing one from the other. Gross pollution is sensible to the sight, the taste, the smell, and we instinctively revolt; lesser pollution, though perhaps not apparent to any of the senses, yields its secret to the chemist's skill; while infinitesimal pollution eludes all, even the art of the chemist himself, revealing its presence only in its fatal effects, the mortality statistics proving the presence of that subtile poison chemical analysis is powerless to detect. Special stress should be laid on this latter point, because the popular cry generally is, where water is suspected, " Let's have it analyzed! " whereas the truth is, beyond a certain point, the chemist can tell us nothing at all about it. Sir Benjamin Brodie, in speaking of the detection of infinitesimal pollution, says:". . . I think you have a much better chance of getting at these relations through accurate medical statistics, properly applied, than you have through chemical analysis, because chemical analysis is one of the poorest things possible to reach those delicate quantities. You cannot get at those small quantities at all; chemical analysis must be limited by our power of weighing and measuring. We can only do those two things. We can weigh and we can measure, and we can do that with certain accuracy, and there we stop; but that accuracy is not capable of being multiplied ad infinitum. It may go on to a certain point, but we cannot go beyond that point."
Having once determined in what pollution consists, then any suspicious water should be unhesitatingly condemned. Colonel Adams says (in the paper previously quoted), "Grounds for distrust in determining the purity of water are grounds for its rejection, especially when brought into comparison with water from a source of undoubted purity."
It has been objected that no water outside the laboratory is absolutely "pure;" that water ordinarily available for town-supply is only relatively pure, and that too high a degree of purity must not be expected, lest the cost of the works be too great a public burden. This is true, abstractly, yet who will have the temerity to draw the line and say: "Our town can and must stand such and such a death-rate, but no more; let us risk it and take our water from this contaminated pond close by, and let the death-rate be so and so, rather than spend so many thousands more in bringing pure living water from the everlasting hills miles away, and thus reduce our death-rate to the minimum!"
The question of cost should never for a moment weigh against the question of purity of quality. Foul, though apparently pure, water may be the cheaper in the beginning, but it will surely be the dearer to the community in the end, when it is remembered that health and life itself tremble in the balance. Cost and quantity should not be underrated, certainly, neither should quality. It is the frequent neglect of this latter element of calculation, in designing works for the water supply of towns, that results in the frightful epidemics usually and impiously attributed to the "mysterious dispensations of Providence," rather than to human ignorance, or cupidity, or negligence. Recently an English clergyman actually preached to his parishioners that a devastating fever among them was a visitation from God upon them in punishment for their sins, while at the same time a gentleman, writing to the authorities to complain of the water-supply, dipped his pen in, and wrote with water from the river instead of ink!
Setting aside now all other sources of water-contamination, let us see what the best authorities say would be the effect on the quality of drinking-water derived from agricultural lands enriched with organic manures, and especially that manure which consists largely of human excreta from privy-vaults and the contents of house cesspools.
Two propositions may here be stated that are perfectly sustained by proof:
1. Any organic matter will poison water, and is not removable except by boiling or distillation.
2. Human excremental matter is the most dangerous organic substance likely to be contained in privy-vaults or cesspools, and its virulence is largely increased when it consists partly of the excrementitious matter of cholera and fever patients.
We will take as an example a compactly-built town of some fifteen thousand inhabitants. Each habitation has its one or more privy-vaults and cesspools, some of which overflow into the few rude sewers built without any systematic plan, and themselves but "elongated cesspools," or, as some one pertinently calls them, "retorts for the generation of poisonous gases." A large majority of these sinks of abominations have no communication with any sort of sewer, but after prolonged conservation, resulting in horrible putrefaction, when no longer tolerable, are finally emptied by hand into carts and hauled away. Adjoining the town is the gathering-ground of the waterworks of thousands of acres in extent, whose waters, discharged into running streams in a long valley, are collected and retained in a dammed-up pond at the foot, and pumped to the distributing reservoir on a neighboring hill. Water-works and sewerage systems should go hand-in-hand; but in this case there is no connection—the latter, indeed, existing only in name. Even this state of things might be tolerable, were it not that, in addition to poisoning the air and the already supersaturated soil, the contents of these vaults are now directly employed to pollute the water-supply. Destitute of any official control, probably more than one-half of the accumulated town filth is annually spread bodily, spring and fall, over a large part of the water-shedding surfaces. The tank-carts employed are at all hours of the day filled at the doorways of the houses, and shamelessly hauled through the public streets, jolting and slopping their foul contents, marking their route by a train of filth on the roadway, while a column of stench in the air, that lingers long after the pestilence-breeding ox-cart has lumbered away in the distance, proclaims adherence to the practices of the dark ages, and defiance to the rules of decency and the laws of health. A century ago, when there was no generally-known method of deodorizing sewage or decently removing it, this sort of thing had to be done, perhaps, but it instinctively sought the cover of nightfall (as the very term "night-soil" implies); but in this incredible case, in the last quarter of the brilliant nineteenth century, in the midst of a civilized community, there is no attempt to disguise the abominable fact!
The water-slopes are thus heavily manured. What is the result? We shall see.
These farms are very rich and valuable, made so at the expense of the water they shed for domestic use. But this sort of fertilizing must not be confounded with what is known as "sewage-farming," a system of irrigation which is declared by the highest authorities to be the best, cheapest, safest, and most inoffensive mode of disposing of all excrementitious and other waste matter, "provided its effluent water does not get into the domestic water-supply." The scope of this article will not admit even a brief description of this mode of irrigation (not manuring), with its appliances of brick, concrete, and earthenware conduits, its valves and sluice-boards, and its trained and careful administrative corps of workmen efficiently supervised. Those interested in this subject (and which is a side-issue here) can consult the "Conditions of Sewage-Farming" as stated by the First Rivers Pollution Commission of England, and reprinted, with much other valuable information appertaining, in the "Report of the Massachusetts State Board of Health for 1876" (pages 276-408), in a paper by Dr. C. F. Folsom, on "The Disposal of Sewage." Many modes of "disposal" are herein described, but such "disposal" as this—sowing pestilence broadcast—was never contemplated by any one. Of course it can be prevented, but it is not proposed to discuss that matter now.
Now, these organically manured slopes are, many of them, very steep, varying, by actual measurement, from one in seven to one in fifty, and flatter. When the heavy rains of spring and fall occur, the effluent water from those slopes is dilute sewage, dilute human excrement, and, especially if the land has been recently ploughed, a large quantity of the surface-soil, and with it the freshly-applied human excreta, and the remaining noxious parts of the previously-applied batch of filth still present in the soil, must necessarily be, and is, washed down-hill and into the water-supply of the town. The English scientific periodical Engineering records that, early in the spring of 1876, "the piers of Vauxhall Bridge were coated with a covering of upward of a foot deep of soil, brought down from the upper portion of the Thames during one tide, and this minor instance is but a slight indication of the enormous deposits cast into our (British) rivers through the washing of the surface-soil from the adjacent fields. . . . The water, before being drawn into the Thames companies' reservoirs, was loaded consequently with soil, manure, sewage, and every imaginable abomination that newly ploughed and manured fields and towns could supply."
Of course, this pollution was on a larger scale than could occur in the case here treated. Nevertheless, if the quantity of polluting matter be less, so is the volume of water polluted, hence the proportion of foulment may be approximately the same. At any rate the fact remains that the water is contaminated, and, as has been already shown, infinitesimal may be quite as fatal as profuse pollution.
The elements that go to make dilute sewage unfit for assimilation in man, especially fit it for plant-food, a fact well known to every gardener. Dr. Folsom says that "a celebrated horticulturist in Brighton, England, dilutes his manure until it has neither taste nor smell." If such attenuated "barn-yard coffee" can have manurial effect on vegetation, what physiological effect—pathologic and hygienic—would it be likely to have when employed as a beverage? This very question is answered in a report to the English "General Board of Health" in 1856, the substance of which is as follows: ". . . It is now generally admitted that the substances which constitute the organic matter of water act injuriously, by no means (necessarily) in consequence of being poisonous themselves, but by undergoing those great processes of transformation called decay and putrefaction, to which all vegetable and animal matter is subject, when no longer under the control of vitality, either in plants or animals. These putrefactive processes either give rise to the formation of poisonous bodies, or they act simply as ferments, generating similar processes of decomposition in the substances composing the animal organism."
The "controlling vitality" of plants and man have widely differing requirements: what is food to one is to the other poison, and sewage polluted water is just what the Brighton gardener uses.
Dr. Corfield says, in a lecture before the Royal School of Military Engineering at Chatham, that ". . . mere passage over the soil will not purify sewage satisfactorily. The effluent water which goes off the land is, to all intents and purposes, sewage." And Mr. Denton, a distinguished engineer and scientist, says, in a lecture before the same school, that ". . . water collected from the surface of cultivated lands, and from the under-drains of cultivated lands, is always more or less polluted with the organic matter of manure, even after subsidence in lakes or reservoirs." Shallow-well water is declared by the Rivers Pollution Commissioners to be the most dangerous of all waters, "whenever the wells are situated, as is usually the case, near privies, drains, and cesspools;" and it is this shallow-well water that Denton refers to when he goes on to say the commissioners declare that "such polluted surface or drainage water (referred to above) is not of good quality for domestic purposes, but it may be used with less risk to health than polluted shallow-well water, if human excrementitious matters do not form part of the manure applied to the land." Mark this, on the highest authority, that shallow-well water, the most dangerous stored well-water known, is safer to drink than the effluent water from such slopes as this article describes. When it is added that the Royal Commissioners, having examined the waters of some four hundred and twelve shallow wells in different geological formations, pronounce them all, with few exceptions, "entirely unfit for human consumption," the force of the objections raised against the water from the foul slopes may be appreciated.
It may be suggested that filtering be resorted to, or the sewage "disinfected," as some are pleased to call certain processes. But the English commissioners say that "as applied to sewage, disinfectants do not disinfect, and filter-beds do not filter. Both attempts have been costly failures." And again they say, "No process has yet been devised of cleansing surface-water once contaminated with sewage, so as to make it safe for drinking." To this the late Mr. Kirkwood, the distinguished American engineer, adds, ". . .If this view of the case may seem to be over-cautious, it is to be remembered that the poison, however trifling, is taken daily, and that, although when in robust health the individual will not suffer from it, it may be sufficient to make itself felt when he is prostrated by sickness, and his powers of resistance to such influences are then proportionally impaired."
It has been supposed that if the sewage be applied to these slopes while the ground is frozen, the greater part, at least, will percolate into the earth, owing to the higher temperature of the sewage and the heat disengaged by continued fermentation, and so be out of harm's way before the advent of the thaws and rains of spring. It has been proved by experiments in Maine, with the thermometer at 0° Fahr., that the sewage disappears soon after it is applied. It would be safer, no doubt, but the "brown scum," which, it is said, remains on the surface, would be thrown down by the spring rains, and other poisonous matter would follow as soon as the plough broke the surface. The danger might, perhaps, be diminished, as in the case of dilution in running water—nothing more.
Too much stress cannot be laid on the death lurking in all manner of human excreta, especially those of the sick. Dr. Folsom, the Secretary of the Massachusetts State Board of Health, and one of the first sanitary authorities, says: "In no case is it entirely safe to drink water which has once been contaminated with human excreta containing the germs of disease, unless it has been exposed-to a sufficiently high temperature or has stood long enough for these 'germs' to become inert. How long this time must be, we do not yet know." And again he says that, "under certain conditions, human excrementitious matter in certain diseases is almost certain poison, producing the parent-disease in great numbers of cases of those exposed to it, with a degree of virulence proportional to its concentration."
The cases on record sustaining this are numerous; two very striking ones must suffice here:
Colonel George E. Waring, Jr., in his "Sanitary Drainage of Houses and Towns," relates the case of an outbreak of "filth-fever" in Over-Darwin, England, a few years ago. "The first case," he says, "was an important one, occurring in a house some distance from the town. The patient had contracted the disease, came home, and died with it. . . . The drain of the closet used by this patient emptied itself through the irrigating channels of a neighboring field. The water-main of this town passed through this field, and, although special precautions had been taken to prevent any infiltration of sewage into the main, it was found that the concrete had sprung a leak, and allowed the contents of the drain to be sucked freely into the water-pipe. The poison was regularly thrown down the drain, and as regularly passed into the water-main of the town. . . . Within a short period 2,035 people were attacked, and 104 died."
The "Massachusetts State Board of Health Report for 1877" records an epidemic of typhoid fever which occurred at Eagley, in England, in 1876. The report says: "A certain small brook had been used by the operatives of a mill, so that 'large quantities of fecal matter' were found on its banks and in its bed. It was known, too, that one of the workmen was ill (it was thought that there was a possibility of the disease being typhoid fever). This brook had formerly been used, two hundred yards below, for domestic purposes, but had generally been abandoned since it had become impure, although two families continued to use it, of whom one had typhoid fever, and the other (who boiled it before use) escaped. This same water continued to be used at a dairy, and was the only supply there. Although there is no positive evidence that the milk was diluted with it, it was acknowledged that the milk cans were washed in it.
"From January 30th. . . . to February 15th, 146 persons were attacked, when the epidemic declined."
After giving further details it is stated that in the town of Bolton, two miles distant, "there were fifty families attacked, of whom forty-seven were supplied with milk from this same daily." The investigating officer reported that "not one household to which the milk was traced did he find entirely free from the disease."
Liebermeister, an eminent authority, says, speaking of the spread of typhoid fever through water-works: "Such infection of an aqueduct is most easily effected when excrements from privies containing the typhoid poison are used as manure on the fields from which the aqueduct receives its supply. In this way originated the epidemic in Stuttgart in the year 1872."
Aside from the water we take into our stomachs, sanitation and sentiment alike demand that it should be wholesome. Denton says: "The water used for personal ablution, and for the washing of the clothes we wear, and the utensils we use in cooking, have a material though not so direct an influence on our sanitary condition." The milk-can case had not occurred when this was written, for, if that be true, he might have put it still stronger.
We can safely conclude that it is the quality of the sewage-matter that determines the character and virulence of its poisonous effects, rather than the quantity of foul matter that may be present in the drinking-water, the taint from the fecal matter of one sick person creating wider-spread havoc than that from hundreds of those "that need no physician."
Long before the milk-can case occurred, the English commissioners said that "really there is no reason whatever to believe that the injurious character of sewage depends, fundamentally, upon the quantity of that sewage; in all probability it far more depends upon the quality of the sewage, namely, what it consists of."
As people generally have a vague idea of what sewage consists, any further than that it is a nasty mess, it may be well, in closing this article, to give the definition of the term "sewage" as applied by the English Rivers Pollution Commissioners. It is "any refuse from human habitations that may affect the public health. . . . Sewage is a very complex liquid; a large proportion of its most offensive matters is, of course, human excrement discharged from water-closets and privies, and also urine thrown down gully-holes. But mixed with this there is the water from kitchens containing vegetable, animal, and other refuse, and that from wash-houses containing soap and the animal matter from soiled linen. There is also the drainage from stables and cow houses, and that from slaughter-houses containing animal and vegetable offal. In cases where privies and cesspools are used instead of water closets, or these are not connected with sewers, there is a still larger proportion of human refuse in the form of chamber-slops and urine. In fact, sewage cannot be looked upon as composed solely of human excrement diluted with water, but as water mixed with a vast variety of matters, some held in suspension, some in solution." In fact, were we to fall into the habit of looking upon it and calling it poison, instead of sewage, and treating it as we do any other poison, one step, at least, will have been taken on the high-road to safety. Surely no civilized community ought knowingly to use water polluted, no matter in what degree, with such filth as this.
Denton says that from the report on the "Army and Navy Diet Scales" he finds that "the estimated quantity of liquid of all kinds drunk in the two services averages 1872 gallons per head per annum, or about two quarts per day. Though this quantity is drunk by adults of the male sex, it is some criterion of the quantity drunk by men, women, and children, and it will not be wrong to assume that two-thirds, or 125 gallons per head, is as much as is actually consumed by a mixed population in a year. Dr. Parkes says that an adult requires daily from seventy to one hundred ounces (three and a half to five pints) for nutrition, but about twenty to thirty ounces of this quantity are sometimes in the solid food." This is what we daily put in our mouths, and it certainly should be pure and sweet. In fact, one way or another, we are pretty much all water. It is said that "the model man weighs 154 pounds, of which 116 is water and only 38 pounds dry matter;" based on which fact, Edmond About has written a curious romance, "The Man with the Broken Ear." Water, then, is of all things the one most essential to our existence, and if three-quarters of our very bodies and a large part of our daily food are composed of this element, then, like Cæsar's wife, it should be "clear even of suspicion."
Although, perhaps, there is no special occasion for it in this connection, attention is invited, in the interest of accuracy, to the popular misuse of the term "water-shed." It is ordinarily employed to denote the area collecting the rainfall, and comprised between the highest and lowest points. Properly speaking, a "water-shed" is "the anticlinal ridge separating one river-basin from another." The highest crest-line of a ridge, therefore, is the water-shed; the lowest area in the valley up to the highest water-level is the water-basin; while the area between these (miscalled the water-shed) may be termed the "gathering-ground," or the "collecting slopes."
- "Report on Water-Supply for the City of Philadelphia," made by a commission of engineers in 1875.