Construction of Wells
It is admitted that humus is one of the best filtering materials for water, and that water from a river full of living organisms is to a large extent freed from them by filtering through a few feet of the humus on its banks. In the past few years Professor E. Frankland has shown that water of singular microbial purity has been obtained from the gravel beds which in places flank the Thames. Such water, one must suppose, is obtained from ground water which has fallen upon the earth, has filtered through it, and is slowly flowing towards the river. The purifying agent in these cases is mainly the living humus which lies upon the surface, although the subsoil cannot be without some effect. These facts must alter our attitude towards surface wells, and must teach us what to a great extent has been admitted—that the purity of surface wells must depend more upon the mode of construction and the surroundings of the well than upon its depth. Wells are polluted by foulness which has reached the subsoil without being subjected to the purifying influence of the humus; and there are many facts which go to show that if foul water gets to the under side of the humus without going through it its purification in the subsoil is far from certain. The Lausen epidemic, the Worthing epidemic, and the pollution of the deep well sunk in the sandstone at Liverpool, seem to show us that percolation through a mile of underground strata entails no certain purification, and that wells 80 ft. or 400 ft. deep are not safe if fissures allow the contents of cesspools, leaking under pressure, to trickle into them. The almost universal condemnation of surface wells and their frequent pollution are mainly due to the fact that we take our filthy and dangerous liquids through the humus in pipes, and thus ensure at great expense that they cannot be subjected to purification by it. If these underground pipes leak, the mischief caused by pollution of wells may be very far-reaching. It is very probable that foul water continuously thrown on the same spot of ground may in time work its way to a well and thus pollute it. Such ground, which is constantly soaked, be it remembered, is never tilled, because tillage is impossible. For ground to be tillable it is essential that reasonable breathing-time should be allowed. I am not altogether sure (although I hardly dare utter such a heresy) that a properly constructed surface well in a selected situation may not prove to be one of the safest sources for water, because it can be inspected with perfect ease, and the fact of accidental leakage into it would become apparent. In this connection it may be well to describe in full detail the well which I have sunk in my garden at Andover, a garden which is rather handsomely manured with human excreta. The well is placed in the very centre of the garden (see fig. [14], p. [35], W) at the intersection of two paths—a broad green path and a narrow asphalted path. This situation was chosen for two reasons: (1) that it was as far as possible removed from any accidental pollution from the sewer in the street; and (2) that in the centre of the garden it would theoretically run the greatest chance of fæcal contamination from the manure used. As the well was sunk solely for experimental purposes this was essential. The garden is on a river-bank and very slightly raised above the level of the water. The well is only some 5 ft. deep, and the water stands at a level (which varies very slightly) of about 3 ft. 6 in. from the bottom. The well is lined throughout from the very bottom to a point some 15 in. above the ground with large concrete sewer-pipes 2 ft. 3 in. in diameter, and these pipes have been carefully cemented at their junctions. Outside the pipes a circle of cement concrete about 4 in. thick has been run in. It will thus be evident, the sides being perfectly protected, that no water can possibly enter this well except through the bottom, all contamination by lateral soakage through the walls being rendered impossible. The well is surrounded by an asphalte path about 3 ft. wide and slightly sloping away from it, and it is encircled by a clipped privet hedge about 5 ft. high, except at those points where the circle of privet is cut by the paths. There is a closely fitting cover of oak, which has an outer casing of lead, and thus all contamination from above is prevented. The water is drawn off through a 2-in. leaden pipe which passes through the outer concrete and the concrete lining pipe, the cut passage for the pipe being carefully closed with cement. The pump is behind the privet hedge, and is provided with a sink and waste pipe which takes the overflow some twenty or thirty yards to a neighbouring stream. In this way the constant dripping of water in the neighbourhood of the well is prevented; for I am very much alive to the dangers attending a constant water-drip, which might be able in time to worm its way through soil and concrete into the well itself. I regard this question of the overflow as one of great importance which is too often neglected. Figs. [22] and [23] show this well in section and plan. The nearest point to the well upon which any manurial deposit of excreta is likely to be made is on the far side of the privet hedge, and the distance of this point from the bottom of the well is 7 ft. All water which finds its way into the well must have passed through at least 6 ft. or 7 ft. of earth, and, of course, the great bulk of the water has passed through a far greater length. Three chemical analyses of this water, one by Professor Frankland and two by Dr. Kenwood, testify to its organic purity, and three bacteriological investigations have given similar indications of purity. A bacteriological examination of the water from the river Anton and the well water, made on April 11, 1895, gave 1,133 growths per cubic centimetre for the river and only 7·5 for the well. Of course there may be a dangerous microbe among this small number, but, on the whole, I think the best guarantee of the purity of the water is the condition of the well, which after four years is as clean on the bottom and sides as it was the day it was made. There has been no appreciable increase of sediment on the bottom, and the pebbles are as plainly visible as they ever were. The well is for experimental purposes mainly, but water for garden use is drawn from it, and during the severe frost of 1895-6 my gardener and some of his neighbours were entirely dependent upon it for household purposes. I seldom go into my garden without drinking some of the water, which is clear and delicious, and my visitors seldom escape without drinking some also. I think the well is a very safe one. It must be mentioned, however, that after very excessive amounts of rain, such as occur occasionally, when the water comes down in a perfect deluge and lies for hours in big pools upon the ground, the water in the well becomes turbid. My belief is that under these circumstances the fine sediment on the bottom is driven upwards by the suddenly increased pressure of the water outside; and I have no reason to think that after these storms there has been any actual increase of sediment, the stones at the bottom remaining as visible as ever. I have never been able to make a bacteriological examination after one of these floods, but hope to be able to do so.
Fig. 22.—Plan of Well, showing its Relation to Paths and Hedge.
Fig. 23.—Section of Well, showing Concrete Lining and Position of Pump.
The question whether such a very shallow well becomes dangerous after a flood is a most important one. It is clearly understood that with my well there is no possibility of flood water entering at any point except through the bottom. It must be recognised that in times of flood with a drowned humus the power of purification may be lessened. On the other hand, my experience leads me to say that it is very difficult (if it be possible at all) to wash fæces out of well-tilled humus by any rain which we get in this country. In the autumn of 1894, in the south of England, we had very severe floods, and I was able to note that the humification of fæces in my garden was, as a consequence, very much delayed. Fæcal matter was visible on turning up the soil for nearly three months after it had been deposited, and the masses of fæcal matter were enclosed in crusts of humus which had been rendered airless and clay-like by the excessive amount of water. This naked-eye test seemed to show that the well had not been endangered, for there were the fæces, and most certainly they had not been washed downwards. When the pores of the soil had been opened by frost the humification of the fæcal matter went forward as usual. This experience seems to enforce what I have said before—that a drowned humus cannot deal with dung. That floods may be dangerous to surface wells we all know, but it will be recognised that the conditions and circumstances of my well at Andover are distinctly different from those of the wells mentioned in the following extract, which were filled with flood water by leakage through their tops and sides.
In the Twenty-third Annual Report of the Local Government Board (1893-94) reference is made by Dr. Thorne Thorne to certain investigations on outbreaks of typhoid fever in certain riverside populations in Yorkshire and Lincolnshire. These investigations by Dr. Bruce Low seem to prove conclusively that the fæcally polluted water of the Rye and the Trent had infected with typhoid fever a certain proportion of the inhabitants who consumed the raw river water. Dr. Thorne Thorne goes on to say: 'Incidentally it transpired during the course of this inquiry that the town of Malton had an altogether exceptional history in so far as enteric fever and diarrhœa in fatal form are concerned. Situated on the Derwent, four miles below the confluence of the Rye with that river, Malton was found to derive its water-supply from the Lady Well, sunk to a depth of 14 feet in the middle oolite rock, and occupying some low-lying land close to the river bank. Into this well river-water gained access as soon as the Derwent rose above a given point, the amount of river-water reaching the well varying from mere leakage through holes and crevices in the banks to complete submersion of the Lady Well by the swollen stream. Gradually it had come to be noted that the outbreaks of fever and of diarrhœa followed on seasons of flood in the Derwent, a river which was referred to locally in 1890 as containing "the sewage of all the towns and villages situated near the Rye and its numerous tributaries.'"
In country places where surface wells are the only available source of water, I strongly recommend that they be made on the pattern which I have been describing.
It is the top of the soil which can break up and assimilate organic matter; the subsoil has no such power. It is a common mistake to bury deeply any organic matter which seems to us to be particularly offensive. In this way we ensure its preservation and endanger the wells. The safety of our wells is directly proportionate to the thickness of the humus, and to place organic matter below the humus is like throwing the dog's bone beneath the kennel instead of into it. The inefficiency of deep burial hardly requires to be mentioned. Bodies buried deep in the subsoil last for years, while those which are placed in the living humus are rapidly destroyed.
I should like to mention that when my well was dug there was found beneath a turf path and about three feet below the surface a large quantity of dead leaves which had probably been deposited in a pit at some long antecedent date. They had undergone scarcely any decomposition although they had been in that position very many years. Again, when engaged in pulling down a cottage my man unearthed an old privy some four feet below the surface. In this privy unmistakable fæcal matter was recognisable. Neither he nor I nor any of the neighbours had any knowledge of any such privy having been in use of late years, and my belief is that these recognisable excreta had been deposited at least half a century ago. Who shall say that these excreta did not still contain spores of all the ills that flesh is heir to? Under natural conditions all dead organic matter falls upon the surface of the ground, and nature is a very sure guide.
CHAPTER III
SLOP-WATER
It is often stated that to deal with excremental matters separately from the slop-water is no advantage either from a pecuniary or sanitary point of view, because:
- 1. Slop-water is as foul as sewage composed of excrement and slops.
- 2. A system of sewers is necessary for the slop-water, and it is not easier to treat slop-water alone than it is to treat a mixture of slops and excrement.
The following tables, from the 'Report of the Royal Commission on Rivers Pollution in 1868,' are given by most sanitarians to show that the difference in degrees of impurity between a water-closeted town and a non-water-closeted town is very slight.
Average Composition of Sewage
In Parts per 100,000
| Description | Total Solid Matters in Solution | Organic Carbon | Organic Nitrogen | Ammonia | Total Combined Nitrogen | Chlorine | Suspended Matters | ||
| Mineral | Organic | Total | |||||||
| Midden Towns | 82·4 | 4·181 | 1·975 | 5·435 | 6·451 | 11·54 | 17·81 | 21·30 | 39·11 |
| Water-Closet Towns | 72·2 | 4·696 | 2·205 | 6·703 | 7·728 | 10·66 | 24·18 | 20·51 | 44·69 |
| In Grains per Gallon | |||||||||
| Midden Towns | 57·68 | 2·926 | 1·382 | 3·804 | 4·515 | 8·078 | 12·467 | 14·910 | 27·377 |
| Water-Closet Towns | 50·54 | 3·287 | 1·543 | 4·692 | 5·410 | 7·462 | 16·926 | 14·357 | 31·283 |
| Description | Midden Towns | Water-Closet Towns |
| Total Solid Matters in Solution | 82·4 | 72·2 |
| Organic Carbon | 4·181 | 4·696 |
| Organic Nitrogen | 1·975 | 2·205 |
| Ammonia | 5·435 | 6·703 |
| Total Combined Nitrogen | 6·451 | 7·728 |
| Chlorine | 11·54 | 10·66 |
| Suspended Matters | ||
| Mineral | 17·81 | 24·18 |
| Organic | 21·30 | 20·51 |
| Total | 39·11 | 44·69 |
| In Grains per Gallon | ||
| Total Solid Matters in Solution | 57·68 | 50·54 |
| Organic Carbon | 2·926 | 3·287 |
| Organic Nitrogen | 1·382 | 1·543 |
| Ammonia | 3·804 | 4·692 |
| Total Combined Nitrogen | 4·515 | 5·410 |
| Chlorine | 8·078 | 7·462 |
| Suspended Matters | ||
| Mineral | 12·467 | 16·926 |
| Organic | 14·910 | 14·357 |
| Total | 27·377 | 31·283 |
This table being not unfrequently quoted in support of the contention that slops alone = slops + excrement, I may be excused if I examine it somewhat critically.
I will take the table in grains per gallon and simplify it somewhat.
Grains per Gallon
| Description | Total Solids in Solution | Suspended Matter | Total Solids in Solution and Suspension | Organic Carbon | Ammonia | Total Combined Nitrogen | Chlorine | |
| Mineral | Organic | |||||||
| Midden Towns | 57·68 | 12·467 | 14·910 | 85·057 | 2·926 | 3·804 | 4·515 | 8·078 |
| Water-Closet Towns | 50·54 | 16·936 | 14·357 | 81·823 | 3·287 | 4·692 | 5·410 | 7·462 |
| Description | Midden Towns | Water-Closet Towns |
| Total Solids in Solution | 57·68 | 50·54 |
| Suspended Matters | ||
| Mineral | 12·467 | 16·926 |
| Organic | 14·910 | 14·357 |
| Total Solids in Solution and Suspension | 85·057 | 81·823 |
| Organic Carbon | 2·926 | 3·287 |
| Ammonia | 3·804 | 4·692 |
| Total Combined Nitrogen | 4·515 | 5·410 |
| Chlorine | 8·078 | 7·462 |
We shall all of us be ready to grant that the addition of excremental matters must be something extra added to the sewage, and that such extra matter must be either in suspension or solution. The fact, therefore, that the total solid and suspended matters is less by 3½ grains in the water-closet towns than in the midden towns can only be accounted for by the enormous dilutions of the excremental matters in the sewage. Notwithstanding this dilution we find that the water-closet town sewage contains 20 per cent. more combined nitrogen than midden town sewage, 23 per cent. more ammonia, and, what is very remarkable, 35 per cent. more suspended mineral matter.
This excess of mineral matter in suspension could only be caused by the precipitation of mineral matters by the ammonia and sulphuretted hydrogen formed by decomposition of the albuminous and other organic matter. This excess of mineral matter in suspension must therefore be taken as a measure of the enormously increased putrefaction in water-closet sewage, a putrefaction probably to a great extent brought about by the millions of microbes which are provided from the human intestines with the excrement, and we must therefore assume that the increase of mineral matter in suspension is an indication that a large quantity of foul putrefactive gases has been given off into the streets and houses of water-closet towns.
This table, therefore, seems to me to conclusively demonstrate that the sewage of water-closet towns is far more bulky and far more filthy and dangerous than the sewage of midden towns.
Sewage is not to be regarded too absolutely from its chemical side. We must use our senses, inclusive of our common sense, in coming to a conclusion, and we must not pin our faith on analyses alone. When I am told that it is of little use to deal with solid excreta, because the liquid household slops alone are as foul and difficult to treat as the complete mixture, I confess I am incredulous.
When I see the housemaid's pail filled with three gallons of soapy water and perhaps a pint of urine, am I to believe that the addition thereto of five ounces of solid excrement, a second half pint of urine, and a square foot of paper, will make no difference to its foulness and cause no increase of difficulty in its purification? Credat Judæus Apella! Such a statement is manifestly absurd.
Again, we must remember that it is the solid excreta which constitute not only the foulest but the most dangerous ingredient of sewage, the only one which has caused widespread epidemics again and again, the one which has hung a load of debt round the neck of every municipality in the country.
The other ingredients of household slops, unlike the fæces, are little liable to contain pathogenic microbes. The urine of a healthy man is, as we all know, sterile when passed. In diseased conditions it may occasionally possess infective power, but this is a speculation rather than a practical fact acknowledged by the sanitarian. A large proportion of cooking-water has been boiled, and is therefore sterile, and the same may be said of the water in which our linen has been washed. Household slops, therefore, are not liable to be really infective.
They are nitrogenous, and consequently, if allowed to stagnate by mismanagement, they become very foul from decomposition, but that they are capable of producing epidemics has not yet been proved. Between excrement and slop-water there is this difference, that solid excreta are foul-smelling ab initio, but slop-water (if we except the smell of water in which cabbage has been boiled) only becomes foul if it is mismanaged.
In places which are not overcrowded a great deal has been done when the wholesome treatment of the solid excreta has been arranged for, and I feel that to neglect the doctrine that 'half a loaf is better than no bread,' and to discourage people from dealing with solid excreta, because they do not see their way quite clearly for the disposal of slops, is most dangerous.
One thing is certain, viz., that if the solid excreta are dealt with by dry methods the liquid sewage will be 25 per cent. less bulky than otherwise would be the case.
I feel sure that if, in our anxiety to prevent the pollution of rivers, we fail to appreciate the biological differences between excrement and slop-water we shall make a mistake, which in the end will be no real advantage to the streams. If, therefore, villages and places where the population is sparse make serious efforts to deal with excreta, they should have at least some breathing-time allowed before the fish in their streams are deprived of the luxuries which they doubtless obtain from kitchen slops.
When fæcal matters are mixed with the slops, the mixture is so offensive that we are compelled to place it at once beyond the reach of the nose or eye, and the presence of sticky fæces and large quantities of paper makes any attempt at filtration practically impossible. Domestic slop-water when fresh is not offensive, and is very rarely dangerous; and by attention to certain details it can be easily dealt with.
Domestic slop-water consists of:
- 1. The waste from kitchen and pantry sinks, which often contains dissolved albuminous matter, food particles, dissolved and suspended fat, a considerable amount of coffee grounds and tea leaves, and sundry odds and ends, the result of house-cleaning, such as fluff, bits of string, little scraps of paper and rags, fibres from brooms and brushes, &c. These materials are very apt to accumulate, and to block drains; and if this form of slop-water is to be effectually dealt with, it is essential that the suspended matter be strained out. The purposes which the kitchen and pantry sinks subserve require, according to Notter and Firth, about 3·75 gallons of water per head per diem; and allowing for evaporation, the slop-water must be less in quantity, so that if we say that these slops average 24 gallons per diem for a household of 7 persons, we shall be not far from right.
- 2. Bedroom slops, consisting of soapy water and urine. Allowing for a daily sponge bath, these amount to about five gallons per head per diem, or thirty-five gallons for a household of seven persons. The suspended matters in these slops (soapsuds chiefly) are in such a fine state of division that they easily filter. They may contain waste matches, a few hairs, a small amount of fluff from towels, and an occasional bit of paper.
- 3. The water from fixed baths amounts to about thirty gallons per bath per diem, and in a household of seven would not probably amount to more than sixty gallons a day. It is so clean that it ought not to occasion any trouble.
Assuming the clothes-washing is not done at home we should have fifty-nine gallons per household of seven per diem without fixed baths, and 119 gallons with fixed baths; and if the washing be done at home, then three gallons per head per diem must be added, or twenty-one gallons for a household of seven, giving a maximum of 140 gallons per diem for a household of seven.
Fifty-nine gallons per diem would put upon an acre of land the equivalent of an inch of rain (22,624 gallons) in 384 days, and the equivalent of an inch of rain on a quarter of an acre in 96 days.
One hundred and forty gallons per diem would be the equivalent of an extra inch of rain on an acre in 162 days.
These amounts are trivial, and if the water be supplied from a private well in the grounds it is evident that, allowing for evaporation, we should pump from the subsoil rather more than we return to the surface. Again, it must be remembered that the house with the greatest amount of slops has, as a rule, the largest curtilage. A mansion containing twenty persons with unlimited baths, laundry, and stables would not probably give more than 40 gallons per head, or 800 gallons a day, which is a trivial amount when considered in connection with a park of 20 or perhaps 200 and more acres.
It is necessary to insist that the amount of slop-water to be dealt with in isolated houses is usually trivial in proportion to the land available for its purification. Tidy was of opinion that, employing intermittent downward filtration for the purification of previously precipitated crude sewage, an acre might be sufficient for 7,000 persons. This would give 1/1000 acre, or about 44 square feet, for a household of seven. At this rate my consulting room in London, which measures 24 × 18 = 432 square feet, would be an area large enough for nearly 70 persons. I think the estimate is too small; but even if one multiplies it by ten it is evident that the amount of land necessary for treating the domestic slop-water of a house is much smaller than might be supposed.
In places where unlimited water is obtained by merely turning a tap these estimates are very liable to be exceeded, especially when those who turn a tap on are too forgetful or lazy to turn it off.
I feel certain that anyone who experiments on this matter as I have done will be simply astounded at the small amount of ground which is necessary.
Critics of the plans which I have advocated, and am now about to advocate, sometimes hint that the whole curtilage of one's house must be unwholesomely sloppy.
Such a statement shows a complete ignorance of the whole subject.
Few, if any, of the writers of hygienic text-books seem to have really studied the life-history of slop-water, and it is matter for regret that in some of these books the chapters devoted to domestic hygiene deal more with patents than with principles, and are illustrated more by woodcuts culled from tradesmen's catalogues than by any practical knowledge possessed by the writer.