CHAPTER XVII PLUMBING IN RELATION TO WATER SUPPLY The "plumbing" of a building, as the term is commonly used, includes the pipes for distributing the water supply, the fixtures for using water, and drainage pipes for removing waste water and sewage, together with fittings and appurtenances of various kinds, all within or adjacent to the building. The "service pipe," which forms the connection between the water main and the building, and the "house sewer," which conveys waste water and sewage from the building to the street sewer or other point of disposal, are included in the "plumbing system" of a building, using the term in a broader sense. Connections for rain water are also included, if the water is discharged through a house sewer or a house drain. Plumbing and water quality The quality of the water delivered by the street mains to the service is often markedly changed by the time the water flows from a faucet of the house distribution system to fill a drinking glass, a wash bowl, or a bath tub. The elements of a lead poisoning are not usually picked up in the street mains but in service pipes and distribution systems of house plumbing. The rust of the "red water plague" is not produced in distribution systems but in water backs of kitchen stoves, storage tanks of hot water systems and hot water piping of buildings. Plumbing materials vary greatly in their resistance to corrosion. Cheap plumbing naturally corrodes more quickly than materials. of good quality. It is also true that plumbers often do not appreciate the serious objections to the use of dissimilar metals in contact. This stimulates galvanic corrosion, the effects of which are illustrated by the familiar slug of red water discharged when a brass faucet attached to an iron pipe is first opened. At fittings corrosion is furthermore accelerated by the exposure of unprotected metal along threaded joints. Galvanized pipe, for example, is deprived of its protective zinc coating at the threads and the un protected metal corrodes rapidly. High velocities of flow and high temperatures also render water more active. The "red water plague" is chiefly a hot water problem. Although it is possible to reduce troubles caused by the corrosion of house plumbing systems, by employing water piping materials that experience has shown to be adapted to the nature of the water, even the best selected materials cannot be expected to withstand the corrosive properties of some waters. Water supplies, therefore, should be so chosen or so treated as to reduce the aggressiveness of the water to the lowest degree that is economically obtainable. The hot water systemis of large buildings are sometime protected against corrosion by physical or chemical treatment of the water before passing it into the distribution system. There are several types of apparatus on the market that accomplish this treatment. They are known as "deactivators," "degasifiers," etc. It sometimes happens that hot water is discharged back into the water mains from domestic hot water systems. In separate dwellings, there are two methods of supplying hot water, known as the "tank system" and the "pressure system." In the tank system the water to be heated is received from an open tank in the attic which is supplied with water from the mains through a ball cock inlet. This separates the domestic hot water system from the cold water direct pressure piping. The tank also serves to take care of the expansion of the water during heating, the escape of air liberated by heating, and the escape of steam generated when the hot water boiler becomes overheated. With this system there is no chance of discharging hot water into the mains. In the pressure system, on the other hand, the heating equipment is connected directly to the house pressure piping. Unless a pressure relief valve is provided on the boiler, no means of escape exists for the air and steam that are driven off when the boiler becomes overheated. When this happens, the pressure developed in the hot water system overcomes the water supply pressure and forces hot water through the service connection back into the street main and may damage the meter. In order to prevent the discharge of hot water in this manner, check valves are frequently inserted in the cold water connections to the boiler and close this avenue of pressure relief. Boiler explosions are then apt to occur and become dangerous to life and property. Hot water pressure systems should, therefore, be equipped with pressure relief valves. These are commonly attached to the hot water boiler and automatically relieve the pressure created when the boilers are overheated. In most cases overheating may be ascribed to unregulated gas heaters. Plumbing and water consumption The arrangement of the plumbing system has an important bearing on the consumption of water and the amount of waste. This is a matter of public as well as private interest, although it is sometimes difficult to distinguish between legitimate and wasteful use. The present tendency in house plumbing is to call for large streams of water delivered rapidly. Faucets for supplying water at sinks and basins are often too big and waste much water. Bath tub faucets, on the other hand, may be large without resulting in waste, because the object of such faucets is to fili the tub rapidly and the outlet is usually closed when filling begins. Bath tubs, however, are less sanitary than showers and probably also less economical in the use of water. Water supply pipes are often installed without due regard to their protection against freezing. The danger of freezing induces householders to let faucets run over night during cold weather. Attempts of this kind to prevent the freezing of exposed pipes result in the waste of large volumes of water. Hot water pipes are frequently run too close to cold water pipes and heat the water in the latter. Faucets must then be left running for a long time before they discharge cold water. The use of cheap plumbing which wears out rapidly and is often left unrepaired is another factor in the consumption of water. Leaky faucets waste much water and broken or unadjusted ball cocks for water closet tanks sometimes discharge large volumes of water unnoticed or without an attempt being made to correct the trouble. Plumbing and water pressure When the supply of water at fixtures is inadequate, it is common for the occupant to complain to the water department that the water pressure is too low or that the service pipe from the street main to the house is too small. The real cause of the trouble is often to be sought in the house plumbing system. Small or cheap water piping presents a high frictional resistance to the flow of water. The friction losses are so great that the water pressure is cut down rapidly in the distribution system and the delivery of water to the fixtures is unsatisfactory. Frictional resistance is increased by corrosion which roughens the pipe surfaces and fills them with rust. If the water distribution piping of a building is of good material and well proportioned, the use of water at one fixture will not prevent water from being drawn from another fixture fed by the same pipe. In order to ensure adequate flow, however, losses of head in passing through gates, valves, meters, fittings, and faucets must be taken into account as well as losses in the pipes proper. Piping that is too small requires high velocities of flow which make the operation of water pipes noisy and cause water hammer that jars the pipe in its support. Frequently rapid opening and shutting of valves also cause water hammer. The use of improper fixture equipment that demands rates of flow in excess of those which the distribution piping can supply is another frequent cause for complaints of low water pressure. Flush valves, for example, are being used more and more instead of ball cock tanks to flush water closets. They demand water at a rate (about 30 gallons per minute) many times greater than needed to fill a ball cock tank in a reasonable length of time and must be fed by large service pipes, meters and distributing pipes in order to operate satisfactorily. It is not economical, however, to use large pipes and equipment in order to meet the requirements of only one or two fixtures. Devices such as flush valves should only be used, therefore, under direct pressure when the sizes of service and distributing pipes required for the general uses of the building are sufficiently large. If installed in small dwellings which are normally equipped with small piping, they should be connected to auxiliary storage tanks. These may be either of the pressure or gravity tank variety. Plumbing regulation Good plumbing is a matter that concerns the public health. The regulation of plumbing is therefore justified under the police power. This principle has long been recognized and in many places regulations governing the installation of plumbing systems have been established by law. In general, however, plumbing regulations only cover the drainage system, of buildings, for the first plumbing regulations were promulgated at a time when physicians and sanitarians were still believers in the sewer-gas theory of diseasenamely, that certain diseases were caused by the escape into dwelling houses of foul air from the sewers and house drains. We know today that infectious diseases are not caused by sewer gas, but we appreciate at the same time that poor house drainage will give rise to insanitary conditions and may result in the spread of disease through cockroaches and other vermin. The Sub-Committee on Plumbing of the Building Code Committee of the United States Department of Commerce adopted the viewpoint that plumbing regulation should cover the water distribution as well as the drainage system and has formulated the following minimum recommendations for dwellings and similar small buildings. Article VI.-Water supply and distribution SEC. 70. Quality of water. accepted standards of purity. The quality of the water supply shall meet SEC. 71. Distribution. The water supply shall be distributed through a piping system entirely independent of any piping system conveying another water supply. SEC. 72. Water service. The water-service pipe of any building shall be of sufficient size to permit a continuous ample flow of water on all floors at a given time. SEC. 73. Water supply to fixtures. All plumbing fixtures shall be provided with a sufficient supply of water for flushing to keep them in a sanitary condition. Every water-closet or pedestal urinal shall be flushed by means of an approved tank or flush valve of at least 4 gallons flushing capacity for waterclosets and at least 2 gallons for urinals, and shall be adjusted to prevent the waste of water. The flush pipe for water-closet flush tanks shall be not less than 11 inches in diameter, and the water from flush tanks shall be used for no other purpose. No water-closet or urinal bowl shall be supplied directly from a water-supply system through a flushometer or other valve unless such valve is set above the water-closet or urinal in a manner such as to prevent any possibility of polluting the water supply. SEC. 74. Size of water-supply pipes. The minimum size of water-service pipes from the curb to the dwelling shall be inch, and to fixtures as follows: Sill cocks. . . Hot water boilers. inch |