CHAPTER II. THE HYGIENE OF HABITATIONS. (Part 4)

water courses. There are two methods of sewering houses by water carriage. In the combined method not only sewage proper is carried away through the plumbing pipes and the street sewers, but also all other waste waters, and especially all rain water collected from the roofs. In the separate system the rain water is disposed of by means of separate pipes, and the sewers proper carry away only the liquid and solid waste matters from the house itself. In the separate system the pipes are smaller, and thus decrease the expense of the plumbing; on the combined system the pipes must be large enough to discharge the sometimes enormous amounts of storm water. The combined system is the one used more extensively. Street sewers are constructed by the municipalities and are made of brick, earthenware, and iron. Every house connects with the street sewer by separate house sewers. PLUMBING. Materials. — The plumbing system of the house consists of receptacles (or as they are termed "fix- tures") which receive the various forms of house waste, and of pipes connected with these fixtures, by means of which the waste matter is carried into the street sewer. x4s the pipes carry waste water and at times considerable quantities of gas, the materials from which the pipes are manufactured must be strong, durable, and water- and gas-tight. The earthenware or "clay" pipes which were for- riJMiuxc 59 nu'rl.\ rxtciisivt'ly used for lioiisc drains and house sowtM's arc (»l)j('ctional)l('. 'V\c\ arc ()hsf)lctc now, and nin^t nHnii(ii»alitics lia\f |)ri)liil)Ht'(l tlirir use within the liousc and hniitcd thcni to tlie short Icnjrtlis needed for liouse sewers, outsi<lc of houses, when they are laid on rocky or soHd ground. 'I'hc only advantage of earthenware is its cheapness; hut. on the other hand, its hrittleness is such that it is impossible to make gas-tigiit drains to withstand any long and con- stant ust'. Karthcuware house drains are veritable channels of filth, emitting foul and offensive odors. Lend. — l^ad is quite extensively employed in the manufacture of piping. It has some advantages in its ductibility. l)ut the ])ipes are heavy, expensive, and easily injured by nails driven into them, by being gnawed through by rats, etc. The use of lead is limited to short lengths of pipe, to branch waste pipes and to small-caliber water pipes. Inm. — The material which is almost universally used for pipes is iron; it has all the advantages of cheapness, hardness, durability, and tightness. Bnis.s-. — Brass, nickel, and other hard-metal pipes might be used were it not for the expense. (Jlass is a good and appropriate material for ])iping. and when its manufacture is perfected it will probably be u-^ed extensively. Joints. The proper joining of tiie several lengths of pipe used in tiie house is of great importance, as otherwise the system cannot be made gas-tight. Earthenware pipes are joined by means of cement. Ivcad pipes are joined by means of solder-wiped joints. Tast-iron pipes are j(»ineil !•> means of lead-ealkeil 60 HYGIENE OF HABITATIONS joints. Wrought-iron and brass pipes are joined by screw joints. Lead j^ipes are joined to iron pipes by means of brass ferrules. Pipes. — The plumbing system within the house consists of several pipes — vertical and horizontal. Vertical Pipes. — The vertical pipes are the fol- lowing : The Rain Leader. — This carries down the rain water from the roof into the house drain. The TVaste Pipe. — This carries down the waste water from kitchen sinks, wash-basins, laundry tubs, etc. The Soil Pipe. — This is connected with the water closets and, usually, with the bath tubs, and carries down the sewage and waste from these. Horizontal Pipes. — The House Drain. — This is the principal horizontal pipe. It connects with all the vertical pipes and carries away the whole house-waste matter into the street sewer. House Sewer. This name is applied to the short length of drain a few feet outside of the house founda- tions which leads to the connection with the street sewer. It is really a part of the house drain. Sizes. — The sizes of the various pipes should corre- spond with the amount of waste matter they are supposed to carry. There is no advantage in making the pipes too large; smaller pipes are apt to be better flushed than larger pipes. A two-inch waste pipe with only two or three fixtures attached to it ought to be sufficient for a private dwelling. The New York rules require a four-inch pipe in tenemant houses where five or more sinks are used. Three- and four-inch soil pipes are adequate in private dwellings; five-inch I'l.lMlilXC Gl pipes are retjuired in teiicinaiit liouses witli five or more water elosets. Brancli waste ])ii)es vary from one and one-iialt' incii for basin and lanndry tnhs to two-ineh pipes for other fixtures; hraneii soil i)i])es should not be less than four inehes in diameter. Ibmse drains and house sewers are from f(>\n- to six inehes in diameter, aoeordinj; to t\v nunilxT of fixtures in the house. The six-inch drains, invariably demanded by municipal authorities, are sometimes entirely too larjie to be properly flushed. Sewer Air. — The materials of which pipes are made should be perfectly water-tijiht, to prevent an- leak- age of the sewage and waste fluids. The pipes should also be (jus-tighi, because the gases generated within the pipes are believed to be undesirable for the inhabi- tants of the rooms in which the plumbing pipes are situated. The plumbing system connects the house with the street sewer, and the same ]iipes which serve to rid the house of liquid waste and sewage matter become, reciprocally, a direct means of entrance for the air and gases in the street and house sewers to the house and rooms. Is this <lesirable? There is still a great deal of misapprehension of the common terms sewer gas and sewer air. The popular idea of sewer gas is that it is a distinct (jns, some- thing like illuminating gas, which is found only in sewers and i)lumbing jiipes, and that its inhalation i- harmful to a great degree. There are some, indeed, who believe that sewer gas is ca])able of ])roducing certain diseases like typhoid fever, dii)htheria, etc; and not so long ago a prominent sanitary inspector 62 HYGIENE OF HABITATIONS asserted that she traced several cases of tuberculous meningitis to defecti^•e pipes under sinks. The theory that sewer gas causes various diseases was once up- held by noted sanitarians, and seriously advocated by Drs. Simon, Richardson, Gorfield, and others equally prominent. As a matter of fact, later research has shown that there is no such gas as sewer gas. What is termed sewer gas is but sewer air, and there is no more reason to term the air in a room "room gas" than the air of sewers "sewer gas." The sewer air may at times be as pure, and more so, than the air of rooms, and, at other times, it may contain the same or more impurities than room air. The impurities ordinarily found in sewer air are an excess of carbon dioxide, carbon monoxide, illuminat- ing gas, sulphuretted hydrogen, marsh gas, ammonia, and other gases found wherever decomposition and putrefaction takes place; there may also be found a large number of bacteria and various microorganisms. This composition of air which at times may be found in sewers, while not liable to directly cause various diseases, is certainly not desirable as an additional mixture to the air in our rooms, air w^hich, without any additions, is rich in impurities. There is no doubt that the inhalation of impure sewer air is inju- rious to human beings, in the same manner as is the inhalation of any impure air, and therefore it is impera- tive to prevent the incoming of air from sewers into the house and rooms. Traps. — As there is a direct connection of the rooms with the sewer in the house-plumbing system, the I'u Miiisa rhi prohlciii is liow to (liscoiiiH'ct tlic li(»us«' trom the sewer and at the sainc tiiiu- leave the i)luml)iiig system to pert'orm it> t'uiictioiis? Tlie i)rol)lein is soKcd 1)\ means of traps. A trap is a bend in a pipe, so construeted as to retain a certain amount of water. Tills water is ealled siiiL and serves as a l)arrier to the baekflow of air from tlie sewer into liouse pipes. Traps arc es])e- eiall' constructed in them, and tlnis cut off eonnnuni- cation between sewer and house. Tlie house is disconnected from the sewer by the main trap on the house drain. This serves as the priii- cil)al barrier to the inflow of sewer air into the house, but there are also additional traps on the branch jiipes under each and every fixture which serve to j^revent the bad air in the house pipes from cominji into the room from and through the fixtures. Thus there are a main trap, the house-drain trap, and a multitude of fixture trai)s. The traps are made in \arious forms, and have innumerable names and shai)es, but all are intended to serxc the same pur])osc. There are also a number of mechanical traps with various devices for strengthening the action of the traj) as a .S7Y//. Of course, as everywhere in plumbing, the simpler the contri\ance the better it is. 'i'he most commonly used traps are the "running trap" on house drain and the "S" traps on fixtures. Loss of Seal. The traps can be depended njjon only as long as their seal, i. r., the water in them, is intact; but if, for any reason, this seal is broken or "lost," it is evident that the traj) becomes useless. There are a number of causes, such as evaporation, 64 HYGIENE OF HABITATIONS momentum, capillary attraction, siphonage, and, per- haps, hack pressure, through which a trap may k)se its seal and thus become ineffective as a barrier to sewer air. Loss by Evaporation. — The water in a trap may evaporate if the fixture over the trap is not used for a long time; hence, house dwellers may find the houses they left for the summer full of bad air on their return, owing to the loss of seal. This evapora- tion can only be prevented by frequent use of the fixture, or by filling in the traps, before leaving and closing up the house, with some oil or other non- evaporable material. Loss by Momentum. — Loss of seal by momentum is due to negligence in pouring into a fixture a large amount of water, suddenly and forcibly, so that the momentum is insufficient to empty the trap as well. This can be prevented only by care. Loss by Siphonage. — A more important loss of seal occurs through siphonage. The water in the trap or seal is suspended between two columns of air, and is influenced by any and all currents of air on either side of the seal. A discharge of water from a large fixture connected with a vertical pipe acts like the drawing of a cork or piston through the pipe, /. c, it creates a vacuum behind it, causes great suction, and draws out, or "siphons" out, any water which may be in the trap. By "siphonage" is therefore meant the emptying of the seal of the trap by the aspiration of the water in the trap as a result of the downward rush of water in the pipes with which the trap is connected. PLUMBING 65 The si])honinf; of traps is a frequent occurrence in larpe houses in whicli the water from fixtures in the toji floors lias a distance to traxcl and falls with trreat nionientuni. Every disciiarge. of a water closet on a top floor will siphon out the seal of the traps of sinks and wash-basins on the lower floors. Loss by Back Pressure. — This iiappens in house- drain traps during bi^ rain storms when the street sewers are overtiooded, and part of the overflow hacks up into house drains where it ina' force back the water of the main traj). It may also occur during a rise of tide in houses near the shore. Wiiat is ordinarily understood by back pressure, however, is the absorption of foul gases b- the water in a trap from the air in the pipes. As the water is exposed continuously to the gases in the pipes this absorption goes on all the time, and thus the gases may enter the room through the water in the traps. Vent Pipes. — The prevention of the siphonage of traps, as well as of the back pressure, has occupied the minds of many plumbers, and various means have been employed to remedy the evil. A number of mechanical traps have been invented, but they all have the one fatal defect, that they are cumbersome and do not prevent the evil they intend to remedy. Actual backing uj) of water in main traps can be prevented !)>' the tide valves. There are a inunber of these oil the market, and most of them serve their j)urpose well. The back |)re>>ure. whi<h consists of the absorption of gases by the water in trai)s, ran very well be pre- vented by a good ventilation of the pipe>. This is 5 66 HYGIENE OF HABITATIONS readily accomplished by the ordinary extension of the vertical pipes above the roof and by the fresh-air inlet. The siphoning of traps in houses of two and three stories, in which the fall of water is not so heavy and the momentum consequently not so great, can be prevented by the ''non-siphoning" traps. It is only in large houses, tenements, factories, etc., that the problem of siphonage demands the installa- tion of a new system of pipes called "vent-" or "back- air" pipes. These run vertically through the houses, and by their branches join all the traps near their crown and thus furnish a column of air for the water seal in the traps. This air prevents siphonage be- cause it is more easily withdrawn during the aspiration process than the heavier water in the traps. The vent-pipe system serves also as an additional means of ventilating the whole pipe system. The objection against the venting pipes is the additional expense. ^Yhile most municipalities strictly demand vents in all houses, there is reason to believe that the practice of installing a special vent system will not last very long, especially in private dwellings. At present the tend^^ncy is toward simplification of the pipe system of the house. In the so-called "one- pipe system" of plumbing the vent pipe is omitted, and siphonage is prevented by the installation of "non-siphoning" traps. PLUMBING PIPES AND FIXTURES. The plumbing system consists of the various fix- tures, such as sinks, wash-basins, laundry and bath j'lJMHisa rii'F.s AM) Fi.\riia-:s (i? tiili->. aiiti the water (•1()M'1>. All these fixtiiro lead into the three main \ertieal pipes within the Irnnx', viz.. irasi-)' and .v'*// pi])es. with the rent piju's aceom- panyinj; tliein. All tiie vertical |)ipes in turn load into the iiori/ontally running; main house drdln which connects witli the street sewer through the short house sewer. House Drain. The house drain is the main pipe. It receives all the drainage from the vertical pipes in the house and carries it to the street sewer. The house drain is not level, hut has a pifch or fall, in order to assist the velocity of the How of its con- tents. The rate of fall siiould n(»t l)e le>> than half an incii to the foot, although some municipalities allow a fall of a (juarter of an inch to the foot. Tiie rate of the fall depends also on the diameter of the pipe. The position of the drain under the house should he ahove the cellar; on the cellar floor, or under the ground. There is the greatest objection to the |)lac- ing of any plumbing pipe out of view; especially is the general practice of iiiding the house drain under the cellar floor very bad, as it conceals the frequent defects of construction, joints, etc., and is likely to cause great damage to the cellar and foundati(»n> by saturating tliem with offensive etlhivia i)efore the defects are detected. When the house drain nms above the cellar it should be properly supported, either by brick j)iers f)r by suitable hangers to the wall. When it runs on the cellar Moor the house drain should rest in speciall- constructed concrete or cement l)e(b. and in treiKJie-^ with proj)er beds foi" the hubs. 68 HYGIENE OF HABITATIONS The house drahi is separated from the house sewer by the main house trap, which is situated near the inside house wall. It should be provided with hand holes for cleansing purposes, and with tide valves when there is a possibility of back pressure by tide or storm. These hand holes should be closed by brass screw ferrules. The fresh-air inlet is a cast-iron pipe about four inches in diameter. It enters the house drain on the house side of the main trap, and extends to the outer air at or near the curb, where, as a rule, it terminates in a receptacle covered by an iron grating in the sidewalk. This form of fresh-air inlet is almost always ineffective, because the iron grating and the fresh-air box are commonly full of rubbish and dirt. The extension of the fresh-air inlet pipe several feet above the ground, properly protected by a wire basket or otherwise, and placed at a distance of at least fifteen feet from windows, is preferable to the ordinary fresh-air box. The Soil and Waste Pipes. — The soil pipes receive the sewage from the water-closets and the bath tubs which are commonly located in the water-closet apartments. The soil pipe is made of heavy cast iron, with lead- calked joints, and is three or four inches in