PHILADELPHIA 
Social Science Association 
HOUSE-DRAINAGE AND SEWERAGE. 
READ BEFORE THE ABOVE ASSOCIATION, FEBRUARY 
I 6th and i Bth, 1878 
GEORGE E. WARING, Ja 
PUBLISHED BY THE 
PHILADELPHIA SOCIAL SCIENCE ASSOCIATION, 
720 LOCUST STREET, PHILADELPHIA. TJJE FOLLOWING IS A LIST OF THE PAPERS READ BEFORE THE 
ASSOCIATION. 
1871. 
Compulsory Education. By Lorin Blodget. Oat of print. 
Arbitration as a Remedy for Strikes. By Eckley B. Coxe. 
The Revised Statutes of Pennsylvania. By R. C. McMurtrie. Out of print. 
Local Taxation. By Thomas Cochran. 
Infant Mortality. By Dr. J. S. Parry. 
Statute Law and Common Law, and the Proposed Revision in Pennsylvania 
By E. Spencer Miller. Out of print. 
Apprenticeship. By James S. Whitney. 
The Proposed Amendments to the Constitution of Pennsylvania. By Francis 
Jordan. 
Vaccinatio7i. By Dr. J. S. Parry. 
The Census. By Lorin Blodget. 
The Tax System of Pennsylvania. By Cyrus Elder. 
The Work of the Constitutional Conventiop. By A. Sydney Biddle. 
What shall Philadelphia do with its Paupers ? By Dr. Isaac Ray. 
Proportional Representation. By S. Dana Horton. 
Statistics Relating to the Births, Deaths, Marriages, etc., in Philaaelphia. By 
John Stockton-Hough, M.D. 
On the Value of Original Scientific Research. By Dr. Ruschenberger. 
On the Relative Influence of City and Country Life, on Morality, Health, Fe- 
cundity, Longevity and Mortality. By John Stockton-Hough, M.D. 
The Public School Systei7t of Philadelphia. By James S. Whitney. 
The Utility of Government Geological Surveys. By Prof. J. P. Lesley. 
The Law of Partnership. By J. G. Rosengarten. 
Methods of Valuation of Real Estate for Taxation. By Thomas Cochran. 
The Merits of Cre77iation. By Persifor Frazer, Jr. 
Outlines of Penology. By Joseph R. Chandler. 
Brain Disease, and Modern Living. By Dr. Isaac Ray. Out of print. 
Hygiene of the Eye, Considered with Reference to the Children in our Schools. 
By Dr. F. D. Castle. 
The Relative Morals of City and Cowitry. By Wm. S. Pierce. 
Silk Culture and Home Industry. By Dr. Samuel Chamberlaine. 
Mind Reading, etc. By Persifor Frazer, Jr. 
Legal Status of Married Women in Pennsylva7tia. By N. D. Miller. 
The Revised Statutes of the United States. By Lorin Blodget. 
Traini7ig of Nurses for the Sick. By Dr. John H. Packard. 
The Advantages of the Co-operative Feature of Building Associations. By 
Edmund Wrigley. 
The Operatio7is of our Building Associations. By Joseph I. Doran. 
Wisdom in Charity. By Rev. Charles G. Ames. 
Free Coinage and a Self-Adjusti7ig Ratio. By Thomas Balch. 
Buildi7ig Syste/7ts for Great Cities. By Lorin Blodget. 
Metric System. By Persifor Frazer, Jr. 
Cause a7id Cure of Hard Ti7nes. By R. J. Wright. 
House-Drainage a/id Sewerage George E. Waring, Jr. 
1872. 
1873- 
1874. 
1875- 
1876. 
i 877- 
1878. HOUSE-DRAINAGE AND SEWERAGE.* 
George E. Waring, Jr. 
I. HOUSE-DRAINAGE. 
A CHIEF justification for the spending of large sums in city 
drainage, is to be sought in the sanitary benefits of the work. 
The first great purpose is to promote the health of the community. 
Believing that the good or bad drainage of our houses has far 
more to do with the sick-rate and the death-rate than the good or 
bad drainage of our streets has, I place the house-drainage ques- 
tion first in order, as it is first in importance. 
It is an unfortunate fact, which we cannot evade, that all human 
life involves the production of refuse matter. The economy of the 
person and the economy of the household, present this constant 
condition. In proportion as individuals and households are con- 
gregated together, does the difficulty increase. In one respect, the 
disposal of refuse matters forms an exception to the general 
law, that “in union there is strength.” So far as possible, sanitary 
authorities should adopt as their motto, “ Divide and Conquer.” 
The more we unite our offscourings, the more do we increase our 
difficulty in their proper disposal. It is a simple matter to care 
for the liquid and solid wastes of a single family, living in a house 
by itself, and surrounded by ample ground; but it is a very diffi- 
cult matter,—it is indeed the most difficult problem with which 
modern engineering has to deal,—to take proper care of the wastes 
of thousands of families, living close together in a town. In the 
former case, the ground itself, in the immediate vicinity of the 
house, affords ample means for safe and easy disposal. In the case 
of the town, where public sewers are required for the removal of 
the fouled waters of the community, we are overwhelmed with the 
volume of that with which we have to deal. 
At the same time, whether the drainage waters of the house are 
to be cared for in its own garden, or discharged into the public 
sewer, the conditions of its interior drainage are essentially the 
* Read before the Philadelphia Social Science Association, February 16th and 18th. 4 
same. We will assume that there is no question as to the ulti- 
mate disposal of our drainage, and that we have to concern our- 
selves only with its removal beyond the walls of the house. 
It is well known that water, containing organic matter, if left 
to itself, becomes fouled by the decomposition of its impurities; 
and that vessels, whose sides have become soiled by dirty water 
which they have contained, soon become offensive. 
Our pipes and drains are made for the express purpose of car- 
rying away waste matters, and even a soil-pipe “cannot touch pitch 
and not be defiled.” Every conduit intended for the removal of 
dirty liquids and semi-solid filth, must become more or less slimed 
by adhesions, and the adhering matter is of a decomposable char- 
acter. Even the thin coating of soap and of the dirt of ablution, 
lining the outlet pipe of a wash-basin, wastes itself away in the 
production of the gaseous results of decomposition. Whether it 
be much or little, so far as it is not washed on to the drain, it 
converts itself into “ sewer gas,” and seeks such means of escape 
as the plumber may have left for it. Even a tin slop-basin, stand- 
ing at the side of a wash-stand, unless daily rinsed after emptying, 
becomes offensive, in spite of its free exposure to light and air. 
Its smell comes, not from' the evaporation of its liquid contents 
when full, but from the decomposition of the slight coating of foul 
matters adhering to its sides after it has been emptied. 
The decomposition, of precisely the same matters, takes place 
inside of the waste-pipe of a stationary basin, but here it takes 
place in a confined space, insufficiently supplied with air. For 
lack of air, the chemical changes are of a different, and are believed 
to be of a more dangerous, character. The resolution of organic 
matter into its gaseous elements, implies the absorption of oxygen. 
So long as this element can be supplied by the air, so long the 
dissolution is of a normal character, producing as its final result 
the simple elements of which all organic matter is chiefly made up 
—sulphur, phosphorus, carbonic acid, hydrogen and oxygen (com- 
bined as water), and nitrogen (in the form of nitric acid and am- 
monia). The intermediate combinations between the organized 
form and the ultimate result, are more or less offensive in their 
odor, but the ultimate products are innoxious and innocuous. When, 
on the other hand, there is not a sufficient supply of air to furnish 
the oxygen required, then this element is taken from the decom- 5 
posing material itself. The decomposition goes on, but, lacking 
its natural food, it feeds on its own body, and the whole process is 
deranged, producing sulphuretted hydrogen, phosphoretted hydro- 
gen, carburetted hydrogen, carbonic oxide, nitrous oxide, and other 
offensive and dangerous gases. 
Of course, the waste-pipe of a wash-basin—only a few feet long, 
and of small circumference—does not contain enough material to 
produce a very serious effect, but it is probable that the foul smell 
we so often get from a basin, comes more frequently from its own 
waste-pipe than from the street sewer with which it is connected. 
The waste-pipe of a butler’s sink is still worse in the character 
of the decomposition of its slime, because it is coated with grosser 
materials; the kitchen waste is fouler yet; and when we come to 
that grand combination receptacle of all domestic foulness, the 
soil-pipe and the drain leading away from it, we may well stand 
aghast at their possibilities for offence and mischief. We are much 
given to ascribing the smells with which we are annoyed to the 
bad state of the public sewer, but surely we have in the pipes and 
drains on our own premises (as these are usually arranged and 
kept), a factory of aeriform nastiness sufficient to account for our 
worst troubles. This unfortunate state 'of affairs we cannot en- 
tirely avoid ; foul substances will stick to the sides of our pipes, 
and, being detained there, will go on and rot and produce their bad 
effect. 
Fortunately, however, we can greatly mitigate the evil; indeed, 
I believe it possible, by the exercise of intelligent care in the plan- 
ning and construction of a house, to reduce it to such a point, as 
absolutely to remove all danger and all obvious offensiveness. 
The perfect sanitary formula would be : 
Allozc no organic decomposition to take place within the dwelling 
or within any drain or pipe connected with it. 
Allow no decomposition to take place under conditions favorable to 
the propagation of unhealthful influences. 
Allozv no air that has once been inside of a drain or soil pipe, to 
enter the house under any circumstances. 
To secure the first condition named, with entire completeness, 
is not now possible, nor is it likely that it will become possible. 
All that we can reasonably hope to do is to reduce the amount of 
decomposition to an insignificant point. Decomposable matters 6 
are retained within our drains in two ways: (i) by adhesion to 
their walls, (2) by retention in water sealed traps, though which 
the current is too slight to carry away solid matters. 
By making all our work as smooth as possible, by avoiding 
horizontal or very oblique courses and irregular surfaces, we may 
much lessen the tendency to adhesion. By arranging for the rapid 
discharge of every vessel, we may give a velocity to the movement 
which will have a good flushing effect. We must depend on these 
means so far as the minor waste-pipes are concerned ; but when we 
come to the main soil-pipe, something more is necessary. 
In my opinion, it is just as important to flush a soil-pipe or a pri- 
vate drain, as it is to flush a public sewer, and I should feel disposed 
to insist upon it in every instance where it is practicable. Let 
there be provided on the top floor of the house, or above the junc- 
tion of the highest waste, some appliance by which from 20 to 40 
gallons of clear water may periodically be poured rapidly into the 
soil-pipe, flushing it, and the drain leading from it, with a force that 
will wash them clean of all filth, and we shall remove one of the 
greatest causes of our annoyance and danger. 
The extent to which the flushing system may be advisable, will 
be governed entirely by the abundance of the water supply, and it 
is a question for the water department to consider how far water 
can be afforded for this use. Its general adoption would probably 
involve the consumption of five gallons of water per capita, per 
diem. In Philadelphia, for instance, this would amount to an addi- 
tion of nearly 8 per cent, to the total consumption. Should it be found 
possible to devote this amount of water to the work of cleansing 
soil-pipes and private drains, it cannot be doubted that the benefi- 
cial effect on the public health would be most marked. 
The second number of our sanitary formula relates to the char- 
acter of the decomposition of such organic matter as is necessarily 
retained in our pipes. We have seen, that in the absence of a suf- 
ficient supply of air, the process of dissolution goes all awry. It 
proceeds in spite of us, and it demands oxygen for its support. 
For want of a better source of this element, as I have already 
stated, it takes it from its own material, and then is set up a pes- 
tilent process of fermentation,—which Tyndall has aptly called, 
“ life without air.” 
If we can devise means to introduce into the immediate pres- 7 
ence of these decomposing substances a constantly renewed supply 
of fresh air, we shall entirely change the character of the decom- 
position, and secure a complete and innoxious distribution of the 
whole material. 
It seems strange that it should have been only within the past 
three or four years, that means for the accomplishment of this pur- 
pose have been promulgated. Indeed, the inventors of different 
processes in England are wrangling over the question of prece- 
dence, and while the evidence adduced shows that the process was 
known years ago, it is only now struggling into anything like gen- 
eral adoption, though its simplicity reminds us of Columbus and 
the egg. 
We have heard a great deal, during the past fifteen or twenty 
years, about the ventilation of soil-pipes, and in New York and 
Boston it has become an almost universal rule to carry a small 
lead-pipe from the highest point of the soil-pipe out through the 
top of the house. More recently, the size of this pipe has been con- 
siderably increased, and it is not unusual to find it equal to that of 
the soil-pipe itself. But all of this furnishes no ventilation. We 
cannot ventilate the shaft of a mine by simply uncovering its mouth. 
We must also supply air at the bottom, to take the place of that 
which is to come out at the top. If, in addition to the opening at 
the top, we make another at the bottom, we immediately trans- 
form all of the conditions. Obedient to the impulse of atmos- 
pheric movement, and change of temperature, a free current flows, 
up or down, almost without ceasing, and furnishes at every point 
the full supply of oxygen needed for perfect decomposition. It se- 
cures, too, the further great advantage of the immediate dilution 
and removal of all gaseous products of decomposition, whether 
harmless or hurtful, whether offensive or pure. 
Our third requirement: that no air which has once been inside 
a drain or soil-pipe, must be permitted under any circumstances to 
enter the house, is at least as important as those which we have 
already considered. 
A properly arranged system of waste-pipes and soil-pipes should 
be regarded as a section of “ out-of-doors ” brought, for convenience, 
within the walls of the house. The pipes, by which this exterior 
air is inclosed, should be of a material which will permanently ex- 
clude it from our rooms. Its joints should be as tight and lasting 8 
as art can make them; its walls should be swept by a freely mov- 
ing current of air, and they should be frequently washed by copious 
floods of water. All communications between utensils, in which 
water is used in the house, and the interior of the pipes, by which 
it is to be carried away, should be constantly and tightly closed 
against all backward movement. When we discharge our refuse 
into a soil-pipe, let the door be tightly closed against its re-en- 
trance. With these conditions, we shall be as free from annoy- 
ance as though we had thrown our wastes out through the win- 
dow of a castle wall and closed the sash behind it. 
Under such an arrangement as I have indicated, our refuse will 
be as completely removed as possible; such traces as it may leave 
on the sides of the outlet-pipe will be subject to copious flushing; and 
such as may still remain, will be decomposed in the presence of 
abundant air. 
Thus far, the efforts of sanitary plumbing have been largely 
confined to the production of a trap whose sealing water shall not 
be subject to removal by siphoning. The old idea was, that the 
discharge of a considerable quantity of water on the lower floor, 
would create a vacuum, which must be supplied by the entrance of 
water through a trap at a higher level. No doubt this is, to a cer- 
tain extent, true, and to this extent relief was obtained by the car- 
rying of even a small pipe to admit air directly from above the 
roof. It was soon found, however, that, although this arrangement 
protected the highest traps, there remained the further difficulty 
that, when water was discharged from above, its rapid passage 
across the mouths of the outlets below so rarefied their air that 
the traps gave way before the atmospheric pressure behind them. 
This latter difficulty has been sought to be remedied by making 
the trap of such form and size that, although air may pass through 
it, its water shall, by its quantity or by its oscillation, restore the seal. 
At the same time that this has been effected, the liability cf 
this trap to retain organic refuse, which, under the old forms, would 
have been carried away, has done much to counteract the benefit. 
Then again, in any case, a water-seal trap performs very imper- 
fectly the work for which it is intended. 
Dr. Fergus of Glasgow, who first demonstrated the liability of 
lead soil-pipes to corrosion and perforation by the action of their 
contained gases, has rendered a no less valuable service to 9 
sanitary science, by his experiments on the absorption and trans- 
mission of gases by water. He. showed that ammonia, presented 
at the outer end of an ordinary water-seal trap, produces its alkal- 
ine reaction at the inner end, in fifteen minutes. Sulphurous acid, 
sulphuretted hydrogen, chlorine and carbonic acid were all transmit- 
ted, so as to produce the chemical effects in from one to four hours. 
In another experiment he produced the rapid corrosion of a metallic 
wire at the house end of the pipe. The practical meaning of this is, 
that water acts with reference to gases, very much as a sponge does 
with reference to water. If our tank has sprung a leak, we had 
better plug the hole with a sponge than with nothing; although 
it will permit the water to exude, it will stop the escaping current. 
On the same principle, a water-sealed trap is very much better 
than no obstacle at all. 
It has been found, further, that in tightly closed rooms, the air 
needed to supply the draught of a fireplace, may be drawn through 
a trap b}/ the displacement of its seal. 
These serious defects have occupied much of my attention. It 
seems to me that there is no way in which they may be completely 
overcome, except by furnishing every trap and every outlet with 
the added protection of a check-valve, which, while opening to pass 
liquids towards the drain, shall close absolutely against any move- 
ment of air towards the house. Such a check-valve will not only 
exclude air which might enter under pressure, or to supply the 
draught of chimneys, but will also form an impassable barrier be- 
tween thewvater of the trap and the air of the drain. 
Let us insert a tight, compressed rubber plug in the top of the 
soil-pipe above the roof, and in the foot of the soil-pipe outside of 
the walls of the house. We can now connect an air pump, having 
a mercury column gauge, at some convenient point, and force air 
into the whole system, until the mercury indicates a certain press- 
ure, say 5 lbs. per square inch. If the mercury stands permanently 
at this point, we may be sure that the work is sound and trust- 
worthy. If it falls, this will indicate a leakage which must be 
sought out and repaired. We can assure ourselves before accept- 
ing the job, that under no circumstances shall we be subject to an 
invasion of sewer gas into our rooms. 
I have thus indicated, somewhat hurriedly, the general principles, 
and the methods of construction, which should guide us in arrang- ing for the drainage of a house. In the construction of new work, 
there will be no difficulty in carrying out these indications quite 
literally. In rearranging the plumbing work of old houses, it will 
often be necessary, for reasons of economy or of expediency, to 
deviate from these instructions, to a greater or less degree; but, 
although I have been called to direct the alteration of the drainage 
of many houses in town and country, I have never yet met with a 
case where the essential features which I have indicated, could not 
be so far applied as to secure absolute immunity from danger. I 
ought to add, too, that I have never examined a single house, no 
matter how new, and how thoroughly constructed, in which serious 
defects did not exist. 
11. SEWERAGE. 
WE come now to the question of disposing of the liquid waste 
of a number of houses through the medium of public sewers. 
The difficulties by which we are met at the very outset, relate (I) 
to the manner in which the air contained in the sewer is affected by 
the presence and the decomposition of the foul materials which 
pass through it, and, (2) to the proper means for disposing of these 
matters after they leave the mouth of the sewer. Besides these 
considerations, and more or less involved with them, there arise the 
questions of size, form, inclination, repairs, ventilation, location of 
outlet, flushing, hand-cleaning, etc. 
Two of the leading principles referred to in connection with 
house-drainage have an equally direct bearing on sewerage. 
It should be our aim to permit no decomposition of organic 
matter within the sewer, so far as it is in our power to avoid it. 
Such decomposition as cannot be avoided, should take place in the 
presence of an abundant supply of fresh air, in order that the pro- 
ducts of decomposition may be as far removed as possible from the 
dangerous character of the gases evolved, when organic substances 
putrefy and ferment, without the presence of sufficient oxygen. 
Proper observance of these requirements is necessary, at almost 
every step of the work, from the first consideration of the project 
to the last stroke of the mason’s trowel. No means have yet been 
devised, and none seem to be promised, which will serve to make 11 
a sewer anything but a disagreeable necessity. By exercising the 
utmost care at every step of our progress, we may so mitigate its 
offensiveness and its danger, that a civilized" community need be 
neither ashamed of it nor afraid of it. 
I trust that the sewers of your city are free from some of the 
grave defects of the older sewers of New York and Boston, which 
have been fitly described as being highest at the lower end, lowest 
in the middle, biggest at the little end, receiving branch sewers 
from below, and discharging at their tops ; elongated cesspools, 
half filled with reeking filth, peopled with rats, and invaded by 
every tide; huge gasometers, manufacturing day and night a 
deadly aeriform poison, ever seeking to invade the houses along 
their course; reservoirs of liquid filth, ever oozing through the 
defective joints, and polluting the very earth upon which the city 
stands. 
This description applies in its entirety to few, if any, remaining 
sewers, but the number of large brick sewers in either of the cities 
named, built in the-first half of this century, which are not amena- 
ble to more than one specification of the charges, is extremely 
small. 
The number of large brick sewers in any city, of however re- 
cent construction, not amenable to some of these charges, is, per- 
haps, even smaller. 
This may seem to many, who have lived all their lives on sew- 
ered streets, to be an exaggerated statement, but I am satisfied 
that a sufficient investigation of the subject will convince them 
that it is not so. 
What are now regarded as the requirements of a thoroughly 
good sewer, may be stated as follows : 
It should be so tight as to prevent its liquid contents from leak- 
ing, or leaching into the ground. 
Its fall, or inclination, which need not be great, should be con- 
stant, so that there may be no sluggish flow, and, above all, no dead 
water at any point. 
It should be so thoroughly ventilated, that the filth which smears 
its walls may always decompose in the presence of an ample sup- 
ply of atmospheric air ; that the gaseous products of such decom- 
position may be copiously diluted and speedily removed; that it 
will be easier for those gases, so diluted, to escape through chan- 12 
nels purposely provided for them, than through pipes leading to 
the interior of houses; and that any pressure brought to bear on 
the contained atmosphere, either by an increase of the volume of 
the flow, by an increase of temperature, by the rise of tide-water 
in its outlet, or by the force of wind blowing against its mouth, 
may find easy relief. 
It should discharge at its outlet, within a very few hours, every 
substance that it has received. 
It should be supplied with such appliances for flushing, as shall 
insure its periodical cleansing of whatever substances that may have 
found lodgment on its walls, save only the slight sliming; which no 
practicable flushing can remove. 
A sewer which meets all of these requirements may be 
regarded as the best device which human ingenuity has yet pro- 
vided, for carrying away the offscourings of houses. No single 
item in connection with sewer construction, has been the subject of 
so much dispute, and is still so far from a universally satisfactory 
solution, as the matter of size. Whether sewers, intended for the 
removal of house wastes, shall be made large enough to remove 
also the water of copious thunder storms, is a question, about which 
engineers are still in dispute. There is much to be said on both 
sides of the question, and I do not profess to be able to decide it 
in a way that shall be universally satisfactory. My own conviction, 
however, is very clear that storm-water should be kept out of the 
sewers, which carry house wastes, where other means can be pro- 
vided, at practicable cost, for its removal. 
Having a firm belief that the sanitary condition of any town is 
influenced more by the details than by the ensemble of its drainage 
work, I shall confine myself chiefly to the consideration of such 
sewers as serve to drain side streets, which are mainly the streets 
of residence. 
I should make such a sewer only large enough,—adopting a 
diameter of six inches as a minimum,—to carry the drainage of the 
houses along its line and a very small amount of rainwater,—say 
the first few minutes’ fall of a shower and the whole flow of a very 
light rain. 
I should prefer to make the sewer of such a size, that the ordi- 
nary forenoon flow, of house drainage only, should fill it half full, 
not admitting more rainfall than would fill it to its greatest capacity. 13 
If we can make sure that at least at that part of the day when the 
discharge from the house drains is most copious,—say from eight 
to eleven in the morning,—the sewer shall be running half full, we 
shall provide, in the best manner, for its thorough flushing by its 
own unaided current. 
The size of sewer requisite to meet this condition is astonish- 
ingly small. For example: a pipe 6 inches in diameter, having an 
inclination of 4 inches in 100 feet, has a capacity of discharge of 
nearly 200 gallons per minute,—say 12,000 gallons per hour, or 
between eight and eleven in the morning, 36,000 gallons. It is 
usual to estimate that during these three hours, about one-third of 
the daily flow is discharged. Such a pipe, then, at such an inclina- 
tion, would be adequate to the removal of over 100,000 gallons per 
day. Suppose, now, that each household numbers six persons, and 
that the consumption of water is gallons per head per day. 
The pipe would therefore serve for the drainage of 500 houses, or, 
supposing it to run only half full between eight and eleven in the 
morning, for 250 houses. 
Allowing a width of only 12y2 feet for each house, it would 
serve for a street over 1,500 feet long, closely built upon both 
sides. 
There is no theoretical objection, if we can devise some other 
means for getting rid of storm-water, to adopting sewejs of very 
much smaller size, and, consequently, of very much less, cost than 
is usual for all of our purely domestic drainage service. 
On the other hand, there is the very great advantage that sewers, 
whose capacity is regulated to the amount of work which they 
have to perform, are quite sure to keep themselves clean. The 
flushing power of their current will be sufficient to carry forward 
to the outlet, or to the junction with a large sewer, every substance 
of whatever character, that can gain access to them,—they being 
protected against the entrance of bulky matters by having no inlet, 
whether from a house or from a street gutter, more than 4 inches 
in diameter. 
It is usual in the ordinary practice of sewerage, in many places, 
to use no pipe smaller than 12 inches in diameter. Such a pipe 
laid on an inclination of I in 600,—or 2 inches per 100 feet,—has a 
discharging capacity of 400,000 gallons per day, and, on the basis 
of the calculation just made, it would, if running half-full, suffice for the drainage of 1,000 houses occupying over 6,000 feet of street 
closely built up on both sides. 
I am well aware, that the use of pipes of small diameter implies 
a strict adherence to what is known as “ The Separate System of 
Drainage,” all the surface water, except the small and foul first flow 
of a heavy storm, and the whole of a light rain, being removed by 
separate channels. I am not so Quixotic as to recommend the 
use of pipes so small as 6 inches for any considerable length of city 
sewer, for, in the present condition of the drainage art, the preju- 
dice in favor of making all drains “ big. enough anyhow,” would 
compel the use of larger sizes. But I should contest the prejudice 
as vigorously as possible, and insist on a reasonable adjustment of 
the size of the drain to the amount of work it would have to per- 
form. 
Let us assume that, as a compromise between the smallest pipes, 
which are theoretically adapted to the work, and the popular notion 
in favor of large conduits, we adopt a diameter of 12 inches for all 
subsidiary drains. Let us see how we may best go to work to 
make such a drain conform to the requirements which I have set 
forth. 
Whether the sewer is made of earthen-ware pipe, of hard- 
burned bricks, or of iron,—the only three appropriate materials for 
the work,—its joints must be made in the most thorough manner, 
and with the best material, lead in the case of iron pipes, and the 
best cement in all other cases. The advantage, under certain 
circumstances, of having a sewer act as a land drain for the removal 
of excessive soil-water is more than counterbalanced, in time of 
drought, by the escape of foul sewage into the ground. 
Practically, it is a matter of extreme difficulty to make a brick 
sewer tight; but pipe sewers, laid on a firm foundation, and jointed 
with tarred gaskets and good cement mortar, are easily made' 
absolutely so. However slight the inclination, the greatest care 
should be taken to secure its uniformity. The less the fall, the 
greater the care required. The requisite cleansing velocity of 120 
feet per minute must be not an average, but a constant velocity. 
Any depression in the grade, causing a less rapid flow, or absolute 
dead water, leads to the deposit of silt, which aggravates the diffi- 
culty. When the inclination of the line is very great, slight devia- 
tions are of less consequence, but, except on steep grades, the constant care of the surveyor should be exercised to maintain the 
exact fall. 
Tightness and regular inclination being secured, insuring the 
constant movement toward the outlet of all foul contents, the 
next great requirement is thorough ventilation. To secure this, 
has taxed to the utmost the skill and ingenuity of all sanitary 
engineers. The use of fan blowers, of tall chimneys, of fires, of 
falling spray, and of all other known devices, has been advocated 
by one and another, and all have been applied, usually with doubt- 
ful success. 
The experience of the world seems to have demonstrated that 
there are but two means by which a satisfactory result may be ob- 
tained. (i) By free communication with the atmosphere, at inter- 
vals not exceeding 100 yards, through manholes covered with open 
gratings; (2) by requiring every house-drain to be in untrapped 
communication with the sewer, and to afford a free passage, of its 
full diameter, through the soil-pipe to an open end above the house. 
Either of these systems produces a reasonably satisfactory result; 
but a combination of the two is necessary to perfect ventilation. 
If every sewer is in free communication with the air, through 
open gratings at each manhole, (and at the intervals indicated); and 
if every house furnishes a 4 inch ventilator, rising high in the air, 
the sewer will, under all circumstances, have such a free circulation 
and such a constant renewal of its atmosphere, that, even though 
it contains more or less decomposing materials, it can never become 
a source of what is popularly known and dreaded as “ sewer gas.” 
Sewers, so ventilated, produce no offence, even in the immediate 
vicinity of the manholes, and are, so far as their effluvium is con- 
cerned, entirely unobjectionable and safe. 
This system of ventilation through soil-pipes, if undertaken at 
all, must be compulsory and universal. We cannot ask Mr. A. to 
furnish a channel through his house for the air of a sewer which 
Mr. 8., and Mr. C. and Mr. D. exclude; but if every man, who is 
permitted to discharge filth into it, is compelled to furnish his quota 
of ventilation, and if there is a free inlet for air at each manhole, 
each soil-pipe will deliver a current which might almost be dis- 
charged without danger, at the level of the street, and under the 
noses of passers by, instead of being sent out into the free air 
above the roofs of the houses. A sewer, so ventilated, will accom- plish all that I have indicated as a necessary requirement, under 
every condition. 
In order to secure a prompt discharge of its contents, it must 
have an inclination which will give its current a velocity of at least 
120 feet per minute, i. c. its current should have this velocity at 
some time during each day. However great the inclination, in 
practice the flow near the upper end will rarely be sufficient to 
overcome the friction due to the width of channel; and the deposit 
of silt will be quite a matter of course. Especially when the ground 
is nearly level, the flow must necessarily be sluggish, until, at a 
considerable distance from the head of the sewer, the constant ad- 
ditions to the stream shall have given it a cleansing depth. To 
overcome deposits of silt, and further to remove the sliming of the 
walls, occasional flushing is important. The efficient means for 
accomplishing this are various, but none seems to me to promise so 
good a result as the recent application, by Mr. Rogers Fields of 
London, of his flush-tank principle. 
By the application of this principle, a large flush tank is made 
to receive all the drainage of a certain number of houses, at the 
head of each sewer,—at least enough to fill it every twenty-four 
hours. As soon as it becomes filled, the whole accumulation is 
driven down the branch lines and through the subsequent main 
sewers with a force sufficient to remove all accumulations. 
A sewer, not too large for its work, arranged as above indicated, 
is as good as, in the present state of engineering knowledge, it can 
be made. 
I regard this question of the construction and arrangement of 
minor sewers, together with the construction and arrangement of 
house-drains, as being far more important to the public health than 
the more obvious matter of the ultimate disposal of the outflow. 
It seems to me, therefore, that the City of Boston, in its pro- 
posed outfall sewers, is beginning quite at the wrong end of its 
work, and is devoting itself to the remedy of a comparatively 
minor evil. As a piece of engineering work, the task which it is 
now undertaking is truly monumental; but, even assuming that the 
result will meet the expectations of the projectors, there will still 
be left to be provided for, the removing from every street of the city 
a source of offence and danger, compared with which, the question 
of ultimate disposal is almost insignificant. 17 
London, a few years ago, spent $20,000,000, in an attempt to 
secure a permanent solution of the outfall question. Recent indi- 
cations all point to the conclusion, that the attempt has resulted 
in failure; and that fresh millions must be spent in seeking a satis- 
factory solution of the terrible problem. 
If London cannot safely pour its outfall into the Thames, miles 
away from the city, discharging it only in the copious ebb tide of 
that river, it becomes a serious question whether Philadelphia can 
always discharge her sewage into the Delaware, at any point to 
which it would be practible to carry the outfall sewage. 
My knowledge of your local conditions is far too little to war- 
rant me in suggesting a remedy; but I will venture to indicate 
certain principles which seem to me applicable to all cities, and 
which may be worthy of consideration here. They relate to the 
disposal of the wastes of the closely built part of the city, and of 
the disposal of the wastes of the manufacturing villages and smaller 
towns which are included within your limits, or which, from lining 
the banks of the Schuylkill [which should be your best source of 
water supply,] tend toward its contamination. 
In England, attempts have been made, in some cases on a very 
large scale, to effect the deposit of matters, held in suspension, in 
large settling tanks, by various chemical and mechanical processes. 
So far as I know, none of these experiments has resulted satisfac- 
torily. When sewage has been discharged into the sea, or, at ebb 
tide, into tidal rivers, the removal of sewage matters has been 
much less complete than was anticipated, largely from the fact 
that the erosive power of the flood tide is greater than that at the 
ebb. 
The sewage of Dover (discharged where experiments with floats 
indicated that it would be entirely removed,) is brought back on 
the foreshore by the flood tide, in objectionable amount. The same 
difficulty is said to exist at Brighton. When the great outfall 
works were built at Barking, 11 miles below London, it was be- 
lieved that each ebb tide, supplemented, as it is, by the fresh water 
flow of the stream, would carry the deposits steadily onward toward 
the sea. It is now found that the greater power of the flood tide 
carries it constantly farther up the stream, and it has appeared in 
alarming quantities quite up to Blackwell. 
What would be the ultimate effect of a similar discharge into the Delaware at League Island, can only be surmised, but the ex- 
perience of London indicates that a similar course, adopted here, 
might result unfavorably, though the greater volume of the Dela- 
ware would be in your favor. 
If we are to assume, from English experience, that, to discharge 
our sewage into tidal rivers, or to attempt its purification by me- 
chanical or chemical deposition, will only result in failure, we are 
driven so far as we now know, to the adoption of one of two re- 
maining methods; (i) the Liernur Pneumatic System or, (2) the 
purification of sewage by application to the land. 
Liernur’s system, which removes all sewage admitted to his 
iron pipes through vacuum chambers, and finally to receptacles 
near his air-pump engines, where it is so dessicated that the solid resi- 
due is salable as manure, is too new to be considered as applicable 
to large cities like Philadelphia, except as a last resort, and after 
careful investigation. It works well in Dordrecht, and in Leyden, 
and after years of experience at Amsterdam the authorities have 
ordered its extension over a large part of the town. At the same 
time, its use in any American town would involve too great a mod- 
ification of our habits of life for it to be now regarded as feasible. 
The process of purification by application to the land has been 
measurably successlul, with greater or less drawbacks, in numerous 
cases in England; but, on the whole, what is there known as sew- 
agefarming has generally proved to be a losing business; and engi- 
neers are divided in opinion as to its future. 
There have been two somewhat extensive experiments with Dr. 
PTankland’s system of “intermittent downward filtration”,— 
Merthyr-Tydvil in Wales, and the other at Kendal. 
These have demonstrated that an acre of porous soil, deeply 
under-drained, so as to be aerated to a depth of at least 6 feet, is 
capable of purifying the sewage of a population of 2,500, so as to 
bring the effluvient to a potable condition. 
The land is laid out in several separate areas, each crossed with 
alternate ridges and furrows. The sewage is accumulated in a flush- 
tank which discharges a sufficient amount to give a saturating flow 
over any one of the areas. Of four areas, three are in use, alter- 
nately,—one each day, or half day, as the case may be. The fourth 
area is kept out of use during a whole year, save when occasionally 
needed for storm-water. At the end of the year this is used as one of the three, and the one which has been longest in use is thrown out 
for the next. The ridges are planted with mangel-wurtzel, cab- 
bage, Italian rye grass, or some other crop of strong growth. 
At each discharge from the tank, the ditches between these 
ridges are filled to a considerable depth. The water settles rapidly 
away to the level of the drains, leaving its impurities attached to the 
interior surfaces of the soil. As it descends in the ground, it is 
followed by fresh air which, during the interval between the success- 
ive floodings, effects the decomposition of the foreign substances, 
and, as is found in practice, the entire purification of the ground,— 
being aided, of course, so far as the upper portions are concerned, 
by the roots of plants with which it is permeated. It is very likely 
that our more frequent severe frosts might operate as a serious 
drawback to the operation of the system, but if, instead of attempt- 
ing to grow grass or vegetables on our ridges, we plant them with 
osiers, it is probable that the shelter which these would afford, to- 
gether with the warmth of the sewage, would prevent serious 
trouble from freezing. 
It may be found that no serious objection exists to distributing 
sewage to these absorption beds through porous conduits, lying for 
a short distance below the surface, and so protected against the 
frost. Certainly this system works perfectly for the disposal of the 
drainage of single houses. 
So far as the closely built part of your city is concerned, I am 
very far from recommending this comparatively new system as ap- 
plicable to your needs. Indeed, a question of such magnitude may 
well tax the most careful study of the most competent engineers, 
and, even then, it is fair to assume that the work would be more 
or less experimental in its character,—but it is an experiment 
well worth trying. 
I am, however, inclined to think that the system of intermittent, 
downward filtration may offer a perfect solution of your problem, 
so far as the towns on the banks of the Schuylkill are concerned. 
Indeed, the case of Merthyr-Tydvil,—with a population of 14,000,— 
furnishes unquestionable evidence of its fitness for such work. It 
might serve, too, for communities like Germantown, and all of 
your smaller outlying settlements; and the more you are able to 
provide for your sewage in detail, reducing your main problem to 
the simplest possible terms, the easier will its permanent solution 
become. 20 
A most important means for still further simplifying this problem 
is to be sought in a thorough system of street cleaning. If we con- 
sider all the difficulties, arising from foul matters admitted to our 
sewers, we shall see that the most expensive and troublesome sur- 
face scavenger that we can have, is the rain that falls from heaven 
and washes the dirt of the public streets into the public sewer. 
Press of Edward Stern & Co.