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Plumbing

In general,plumbing refers to the system of pipes,fixtures,and other apparatus used inside a building for supplying water and removing liquid and waterborne wasters.In pratice,the term includes storm water or roof drainage and exterior system components connecting to a source such as a public water system or a point of disposal such as public sewer system or a domestic septic tank or cepool.The purpose of plumbing systems is,basically,ti bring into,and distribute within,a building a suplly of safe water to be used for drinking purposes and to collect and dispose of polluted and contaminated wastewater from the various receptacles on the premises without hazard to the health of occupants.Codes, regulations,and trade pratices are designed to keep the water system separated from drainage systems;to prevent the introduction of harmful material such as chemicals, micro-organisms, and dirt;and to the keep the water system safe under all operating conditions.These protective codes also are designed to prevent flooding of drainage lines,provide venting of dangerous gases, and eliminate opportunities for backflow of dangerous waste water into the water system.It is eential that disease-producing organisms and harmful chemicals be confined to the drainage system.Since the time of Moses man has been cautioned to dispose of his wastes safely, and cleanline has been related to the availability ot water and aociated with social coustom.Early man often lived near a water source that served as his water supply and drainage system in one.It was also his bath.Latrine-like receptacles with crude drains have been found in excavations in the Orkney Islands of Neolithic stone huts at least 10,000 years old.Both a water system and piping used as drainage fashioned of terra-cotta pipe were part of the royal palace of Minos in Crete, about 2000BC.The palace also had a latrine with water-flushing reservoir and drainage.Nothing comparable to it was developed in Europe until the 18th century.Even the equipment of the modern bathroom, though much improved with hot and cold water under preure and le crude provisions for drainage, is in concept little different from the Minoan version.It was out until the end of the 19th century that advance in plumbing practice were given serious attention as an integral part of housing.A building plumbing system includes two components, the piping that brings potable water into the building and distributes it to all fixtures and water outlets and the piping that collects the water after use and drains it to a point of safe disposal.Water systems.When a building is served by a public water system, the plumbing begins at the service connections required to make water available at outlets serving the fixtures or equipment within the building.Many premises in rural areas are not served by public water supply.These may include private dwellings, apartment houses, hotels, commercial centres, hospitals, institutions, factories, roadside stands, and restaurants.Public water supplies have surface water or groundwater as their sources.Large water system are almost entirely supplied with surface water.In smaller communities and in certain areas groundwater is obtained from wells or springs.Independent semipublic, industrial, and private-premise water systems frequently take water from wells on the premise but may, under certain condtions draw water from a spring, lake, or stream.Public water systems supply treated water meeting public water-supply drinking-water

standards.Private-premise systems are expected to provide water of equal quality, and to do so the private system requires a water-treatment plant including chlorination as a minimun and poibly sedimentation(settling out of solid particles)chemical treatment, primarily for softening, and filtration.Water is supplied to fixtures and outlets under preure provided by pumps or elevated storage tanks or both.In some installations a pump controlled by a preure-activated switch on a preurized storage tank takes water from a well and pumps until the upper limit ot preure for the system has been reached.If water is being used at the rate it is being pumped., the pump operates continuously.Elevated storage tanks are usually equipped with high-and low-level-float control switches to activate the pump.When the tank gets loe the pump starts and continues pumping until the tank is full.A storage tank may be constructed as illustrated in Fig.1, or it may be located on the roof of a high building.Water from the tank feeds the distribution system by gravity.Water flowing through pipes causes a lo of head due to friction.Since building piping systems are designed to deliver water at the required outlet preure, pipe size is a critical variable.Plumbing codes have tables and graphs to show typical water demandsof fixtures and outlets in a building.If the required water demand is not met because of undersized piping or underpowered pumping, the preure dops and some outlets may have little or no water flow.Pumping codes usually specify preure and rates of flow for the fixtures in a building.The total amount of water that may be needed to supply the demand can be calculated from tables of fixture water demand.Minimum pipe sizes for different fixture in a building are specified in plumbing codes.Since it is uneconomical to design a water piping system that would provide flow with all outlets open simultaneously, judgment and experience are used to determine the probable maximum simultaneous demand.Average daily water requirements vary according to the type of premises being served.A single-family dwelling unit averages from 20 to 100 gallons(80 to 400 litres)per day.Apartment house occupants use le.Special users such as hospitals and industries usually require far greater allowances.Drainage Systems.Drainage of residential building includes the collection of sanitary wastes and roof drainage.The sanitary wastes are collected in soil pipes and stacks usually made of cast iron, although certain portions of connecting pipe may be galvanized iron.When corrosive liquids are collected, as in laboratories and industrial plants, the system may include plastic or gla pipes or coated piping.The joints, bends, tees, elbows, wyes, and many other special fittings are designed to carry away wastes without having obstructions in the pipe or creating condtions that will cause clogging if some large object is dropped into a fixture or a receptacle.Cleanouts and receptacle outlets are provided with screens or gratings to prevent the entry of clogging materials.The entire piping system is sized so that the smallest size is at the fixture outlet.Plumbing codes specify the minimum sizes for drainage connections and the standards applicable to all pipe and fitting materials.Normally all building drainage is constructed so that waste water flows by gravity to the main house drain.The house drain is usually connected outside the building to a gravity-flow house sewer that leads to a public sewer on a point of treatment.In large buildings such as apartment house, commercial buildings, hospitals, and industrial plants, the house drain may be lower than the point of discharge.Wastes are then discharged to a sump, or storage pit, and all of

the building drainage is lifted by pumps or pneumatic ejectors to a point of discharge to the exterior sewer system.These lifting devices empty water from the storage sump on a cycling basis activated by float controls that prevent flooding of the storage area.Such units are usually installed in duplicate and often have alternate sources of power such as a diesel-or gasoline-power generator for emergency pumping.Roof drainage is collected in gutters and leaders and taken by appropriate piping to a point of discharge permitted by law.Isolated dwellings may drain to surrounding ground, while larger buildings have a drainage system similar to the sanitary system that connects into a public storm-water sewer system.Home disposal systems are used in rural areas.The house drain is connected to a septic tank with a tile drainage field or to a cepool.The septic tank removes heavy solid materials from the waste, and the effluent or treated water is allowed to percolate into the soil through buried, specially constructed, rock-filled trenches over which tiles with open joints are laid.Enough trench must be constructed to allow percolation without flooding the surface of the ground.The effluent from septic tanks contains disease-causing bacteria and cannot be allowed to flow directly into streams or underground waters.Health codes and regulations specify the sizes of home disposal units and control the discharge of effluent.Premises often have other water uses including swimming pools(both outdoor and indoor), ornamental pools, fish pools, and fountains, These require water and are part of the plumbing system.Since swimming-pool water is easily contaminated by bathers, it must either be replaced frequently or filtered, chlorinated, and recirculated.