Read Ebook: Bad Drains; and How to Test Them With notes on the ventilation of sewers drains and sanitary fittings and the origin and transmission of zymotic disease by Reeves R Harris

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PAGE BAD DRAINS, AND HOW TO TEST THEM 1

SEWER VENTILATION 32

THE ORIGIN AND TRANSMISSION OF ZYMOTIC DISEASE 56

BAD DRAINS; AND HOW TO TEST THEM.

In many cases it has been but a fashionable term to describe cases which had the appearance of gas poisoning, but did not owe their origin to drains; but rather to the heated and impure atmosphere of rooms, late hours, and the sudden change from heat to cold. If there have been a few hundred cases where "bad drains" were supposed to have caused the illness and such was not the case, there have been thousands of others where the disease originated from them, but was taken as a matter of course, or as one of the frailties of the human frame, when undoubtedly the cause was "bad drains."

It is a most remarkable thing, that whilst on the one hand we have the medical profession energetically working to find out defects in the planning of drains and sanitary fittings, and writing articles on them, we have on the other hand surveyors and others who have treated the matter as a doctor's fad.

During the last five years scarcely a medical conference has been held without the question of "bad drains" forming one of the principal subjects discussed. Medical officers of health have made stirring speeches and reports to Local Boards; but where is the surveyor who has had the energy to do the same unless it has been actually forced upon him? It is a curious but noteworthy fact, that nearly the whole of the evils of badly constructed drains, and the principal improvements in them, have been forced on surveyors, builders, and plumbers by the medical profession and the public.

The reticence shown by surveyors in dealing with "bad drains" may be attributed to their unwillingness to acknowledge the errors and defects in works already executed. These works were, at the time, executed according to the theories adopted by the most eminent engineers in the profession, and it would be considered unprofessional to admit errors.

There is scarcely a district where the branch drains are trapped into the main sewers with an efficient water-seal. Surveyors feel that to acknowledge this would be tantamount to acknowledging a want of professional knowledge or neglect of duty on their part.

Now, strictly speaking, this could not be the case, and a surveyor could say that these now known defects were not previously known by the most eminent engineers, and especially with regard to sewer-gas, its treatment, and action on the public health. Boldly facing the matter and advocating that the drainage under his charge should be so perfected that no medical man could point to it as being detrimental to health, if it entailed an unusual expenditure, coming from the surveyor he would carry the Board with him, and in doing so would make his position at the Board doubly secure.

To prove this we have only to refer to reports made by engineers during the last fifteen years on drainage schemes, compare the results of the theories laid down, and note the instances in which they have failed, especially those in connection with sewage farms and the ventilation of sewers.

I will quote a few extracts from these reports:--

"No injury to health can possibly take place from gas issuing from properly constructed gratings fixed in the middle of the road, and if one is a nuisance, dig down and put in others until the nuisance is removed."

This has certainly not been the case. You may dig as many holes as you like, and put in as many gratings, yet some will be injurious to health.

In describing sewage farms, they were described as being the means of securing a large revenue to the Local Board by the excellent crops grown, one engineer stating that persons could walk through them with as much pleasure as through a flower or kitchen garden; but practical experience has proved this to be incorrect: and although these statements were made in good faith, they have not been realised.

You may regulate the irrigation of a sewage farm to such a nicety that no odour from the sewage is perceptible in the district; yet the atmosphere will contain poisons which will have a very detrimental effect on the health of those living there.

For a few years after sewage farms have been laid out, they pay, and you get good crops from them, but after that the ground becomes so soured that the farm is almost useless.

In face of these facts no surveyor should hesitate to bring forward known improvements to his Board.

Many owners of property have recognised the importance of adopting the best sanitary measures for their houses, although in some cases it is only a plea to let or sell their property. As an instance of this, some time ago I was in search of a house in the suburbs, and met with one described as standing on good gravelly soil, with good drainage and perfect sanitary arrangements. The builder and owner took me over the house, and on reaching the kitchen pointed out with some degree of pride that the sink was cut off from the drains, and stated that the drains were constructed on the most "scientific principles."

Now although scientific plumbers have done good work in making our dwellings more healthy, they have in many cases overdone the matter. The fact of their displaying conspicuously, on signs and billheads, "Sanitary work executed on the most scientific principles," is not always a guarantee that a healthy house can be received from their hands.

In the house above referred to, everything to the eye appeared sound and good, but on the house being occupied, a disagreeable odour was noticed in the kitchen, and in some of the lower rooms. The sink-pipe, which was pointed out by the builder as being "cut off," ran from the sink trough without a trap or water-seal of any kind, and through this pipe, when the doors were shut, the air was supplied to the building at the rate of 180 feet per minute. The back of the W.C. was ventilated from the outside to give free ventilation to the space under the seat, and through the ventilators the air came into the house, which supplied the bedrooms, passing over the pan, between it and the seat.

The above is an illustration of a house where the sanitary arrangements were supposed to be on the most scientific principles! Fresh air being supplied to bedrooms by passing over the closet-pan, and in the kitchen and rooms below by passing through a 2-inch sink-pipe. This is one of the many cases that may be mentioned to show the necessity of testing any system of drainage and sanitary fittings.

This is not an unusual occurrence, as thousands of similar cases exist, where the principal air supply passes over sanitary fittings or through apertures which bring it in contact more or less with decomposed matter. In a building where a number of fireplaces exist, a constant current of air is passing in from the outside, which after mixing with the air in the building escapes up the chimney. An ordinary chimney extracts from the room from 60 to 120 cubic feet of air per minute, thus in a ten-roomed house you have going out of the chimneys at least 1000 cubic feet of air per minute. When the house is closed this large volume of air is drawn into it through apertures offering the least resistance, whether it be ventilators in the w.c., kitchen sinks, or drains in the basement , over sanitary pipes or through doors and windows. Whichever point offers the least resistance, there the supply to feed the chimneys will come.

The injurious effects on the health of persons who occupy buildings that take in their air supply through unclean apertures are too well known to those medical men and others who have had experience in sanitary matters, and it can be only estimated by results. I could enumerate cases where the health of the inmates and the death-rate were conclusive evidence to prove the disastrous effects produced by air being supplied through such inlets. One case in particular, which consisted of eight blocks of buildings planned exactly alike. The drains were cut off on the outside at the foot of all soil-pipes, and a second disconnection about 50 feet from the building. In one building the basement was drained into the branch drain with a trap in the inside, and from the quantity of water and soil which flowed through this branch drain the basement trap was constantly being siphoned, leaving a 6-inch air supply into the building through 50 feet of drain. This, combined with 200 feet per minute through the W.C., had the effect of causing an unusual depression of spirits in the occupants of this building, and more deaths occurred in this one block than in the whole of the others.

It does not require a large amount of scientific knowledge to ensure a healthy building. What is required is sound pipes, the area of them in proportion to the work they have to do, tight joints, and a knowledge of ventilation. Nothing must be left to theory. A pipe either leaks and lets out the soil, or it is sound. If it is sound, sewage matter can be carried through it anywhere without the slightest injury to health or unpleasantness of any kind. Pipes can be ventilated without traps being siphoned, and the gases from sewers and soil-pipes treated so as to ensure healthy buildings at a moderate cost.

As a rule, the first intimation of any defect in the drainage system of a town or the sanitary fittings of a building is given by the medical officer of health or the medical attendant of the family, whose attention has been forcibly drawn to it by the serious illness of the inmates.

It is no unusual occurrence, that after the medical officer, surveyor, and inspector of nuisances have made a minute inspection of a building, they leave it without discovering defects which exist in pipes carefully cased over, or in the sanitary fittings.

To detect the manner in which poisons from drains are thrown into a building and inhaled by the occupants, is oftentimes not an easy matter. In many cases the drains have been so cut about and additions made to them, that to trace defects or even the number of drains which are attached to the branch drains or sewers, a considerable amount of excavating is necessary.

The system described in these pages is intended to prevent in a measure this excavating, and to enable a person above the ground to determine the number, capacity, and state of the drains underneath the surface, as well as to more readily discover any imperfections in soil-pipes and sanitary fittings.

When sewers are laid to a town or district, it is the practice of the authorities to let the work by tender, the lowest tender being oftentimes accepted; consequently it is in the interest of the contractor to get the work done as quickly and cheaply as possible.

It is impossible for the engineer, or clerk of works, to see the whole of the work done, and the result is that a large quantity of bricks which form the sewer are not properly bedded. Liquid sewage finds its way through the joints of the brickwork and percolates through the soil, in some cases to a very considerable distance, contaminating the water it mixes with on its course, and oftentimes it forms a putrid mass under the basement of buildings which happen to be of a lower level than the sewers. To prevent this, a clause should be inserted in the contract that each length of drain or sewer should be tested by atmospheric pressure, say 5 lb. to a square inch.

The top of the sewer should be as tight as the bottom to prevent any gas escaping through the sandy soil or rubble which may be filled in around the sewers or drains.

Leaky sewers and badly-jointed pipes under the soil should never be allowed, yet the danger is not so great in them as in those pipes laid above the ground. Joints to these pipes so often leak that without testing them thoroughly when laid, one leaky joint would cause an unpleasant odour in a building for years without its source being discovered. The reason of this is, that the current of air passes through buildings in a thousand different ways. I have known a sickly odour to come from a cupboard on the first floor of the wing of a building some 60 feet from any soil-pipe or grating; one case in particular, that of a nursery cupboard. This occurred through a leaky soil-pipe from the closet in the basement of the building.

From the planning of the building the chimney near the cupboard had the greatest draught of air in the house, and the air which supplied this chimney came principally from the basement. The sewer gas from the leaky joint, being of a heavier gravity than the atmosphere of the house, was carried along the floor unobserved to this particular room, filling at night, when the fire was not burning, this cupboard, which contained linen, and this held the impurities given off from the leaky joint in the pipe.

Many cases of a similar nature could be mentioned, where families will never recover the loss sustained by them through similar leaky joints in the soil-pipes.

Insufficient fall to sewers does not often occur in those laid under the supervision of engineers, but it is in the branch drains connected to them where so many blunders are made. Oftentimes one part of a drain is laid almost level, whilst another part is laid with a steep gradient. This facilitates the choking of drains, and the siphoning of traps.

Some persons lay drains from houses to the main sewer or to branch drains which are altogether out of proportion to the work they have to do.

The smaller the drain is kept the better, but the diameter should be regulated according to the quantity of water and soil flowing into it, taking into consideration the possibility of additional inlets being added.

The best plan is to collect the number of inlets or supplies to the drain, compare them with the gradient to which they are laid, and put in a drain which, if all the inlets are supplying water at the same time, would not fill more than nine-tenths of its area.

In some cases I have seen a 9-inch drain laid from a house having only two closets, sink and bath outlet attached. If the whole of these were used at the same time, the area of the flow into the drain would only be 7?696 inches, but in the 9-inch drain the area would be 63?617 inches, or nearly nine times the size required to carry off the water and soil.

The whole space not occupied by water and soil is filled with gas, which extracts poisons from sewage and distributes them at outlets according to the displacement caused by the water and soil entering and flowing through the drain.

Architects and builders laying drains to houses or buildings should discard the theories of any persons who do not keep to this rule: that the smaller the drain is, the better, providing it does not fill; and the least quantity of gas there is in the drain, the less dangerous will be the poison in the gas when discharged through openings or gratings. The reason of this is, that in a small drain only a small quantity of the sewage is exposed to the action of the gas in transit; whereas in a large drain the greater portion of the sewage is exposed, thus increasing its decomposition.

When storm water from houses or land enters drains, great care should be taken to form openings or inlets near where drains are likely to fill, as the injurious effects of trap siphoning are of serious consequence to health.

In many cases the construction of new drains and sewers in a district have been simply a waste of money as regards improving the health of the inhabitants, and numerous cases of zymotic disease, and in some cases an epidemic has occurred where previously such diseases were almost unknown. This is caused principally by connecting old drains to the new drains leading to the sewers.

In cesspits and old drains the soil and putrid matter have been for years allowed to accumulate, and the poison from such matter, when distributed into the open air through gratings in the new sewers or into houses, is, when inhaled into the system, the cause of these zymotic outbreaks. In tracing these old drains and in preventing stagnant gases from remaining in any portion of the drain, the engineer or architect cannot pay too much attention, as confined gases when charged with poisons from putrid matter are the principal factors in producing disease.

Many persons place a well-constructed trap at the inlet, and another some distance along the drain, say at the end of a building or grounds, without any ventilation between the two traps. In fact this used to be a common occurrence; but it should never be done. If the drain should be a 6-inch one, and the traps 50 feet apart, the amount of gas between the two traps would average 9 cubic feet, and this gas would in the ordinary working of the drain remain for years, getting more poisonous the longer it remained undisturbed. The owner of the house, knowing that he had a good trapped drain connected to sewers, would feel himself safe, and naturally think his house healthy. Far better for him if the house were drained into a ventilated cesspit, as when the gases in the drain became released, which may occur by the siphoning of the traps at the house-connection, the danger would be equal to the emptying of a disused cesspit, and carrying the contents through the house. The more a person tests the working of gas in sewers or drains the more he will find that branch drains from their construction supply the poisons which render the gases in the sewers themselves so noxious.

In 1880, whilst engaged in tracing the course of an outbreak of typhoid, I made a series of experiments with a view to trace the source from which the disease emanated, and every experiment proved that the origin of the disease lay in the gases which were in contact with putrid sewage matter, existing in old drains and cesspits attached to the sewers as well as in the gases which were confined between traps. The distribution of the disease was due to the imperfect construction of the sewers, drains, and sanitary fittings.

The most successful experiment, and the one from which the greatest result was obtained, and which I have ever since most successfully used, was in determining the state, size, and condition of the drains underground, and also that of the house or buildings, by measuring by compression the gas contained in the sewer or sanitary fittings. The principal cause of its distribution was the compression of the gas between the water-traps, the siphoning of house-traps leaving at times a free passage for the gas to enter the house.

The amount of compression or displacement necessary to force the gas in bulk through the traps has been accurately measured, to know what quantity of liquid was required to be thrown into a drain or sewer of any size to force the gas in bulk through the water-trap. The lifting power of the gas on the water by compression was found to be 1/300 part of its bulk. Thus, if a drain perfectly sound, and sealed with a water-seal each end, held 300 feet of gas, 1 cubic foot of water thrown into the drain would force the gas in bulk through the water-seal.

It became evident, that if both ends of any drain were sealed with a water-trap or otherwise for testing, the capacity of the drain or leaks of any kind could be determined without excavating.

As it was inconvenient to watch the working of the drain through the traps, I constructed an instrument called a detector to observe the working of the atmosphere in the drain. This instrument, or a gas-pressure gauge, when attached to the drain, will denote by the rising of the liquid the amount of compression in the drain. This, when compared with the quantity of water thrown into it, will give the size and capacity of the drain, and will also indicate any siphoning of traps or leaks which exist in any of the sanitary fittings of the house.

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