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1、IIP a r tWATER AND WASTESEach building has a sanitary plumbing system that chan- nels all the waste downward through the building to the municipal sewer or a septic tank below. The sanitary system begins at the sink, bathtub, toilet, and shower drains. It carries wastewater downhill, joining pipes f
2、rom other drains until it connects with the sewer buried beneath the building. The sanitary system has large pipes to avoid clogs. Since the system is drained by grav- ity, all pipes must run downhill. Underground pipes for sewage disposal are made out of vitrified clay tile, cast iron, copper, conc
3、rete pipe, polyvinyl chloride (PVC) or acrylonitrile-butadiene-styrene (ABS) plastic. The large size of waste pipes, their need to run at a downward an- gle, and the expense and difficulty of tying new plumb- ing fixtures into existing waste systems means that the interior designer must be careful i
4、n locating toilets. Until the advent of indoor plumbing, wastes were removed from the building daily for recycling or dis- posal. Historically, table scraps were fed to animals or composted. Human wastes were thrown from windows into the gutters of the street, or deposited in holes be- low outhouses
5、. Urban inhabitants continued to dump sewage and garbage in gutters until the 1890s. Rural peo- ple dumped wastes into lakes, rivers, or manmade holes in the ground called cesspools, which were fed by rain- water or spring water. These cesspools generated foul smells and created a health hazard.In t
6、he 1700s, shallow wells, springs, or streams pro- vided potable water for farms. Widely separated dry-pit privies (outhouses) produced only limited ground pol- lution. By the nineteenth century, natural streams were enclosed in pipes under paved city streets. Rain ran into storm sewers and then to w
7、aterways. When flush toilets were connected to the storm sewers later in the nine- teenth century, the combined storm water and sanitary drainage was channeled to fast-flowing rivers, which kept pollution levels down. Some sewers continued to carry storm water only, and separate sanitary sewers were
8、 eventually installed that fed into sewage treatment plants. Older cities still may have a combination of storm sewers, sanitary sewers, and combined sewers, in a complex network that would be difficult and expen- sive to sort out and reroute.WASTE PIPING NETWORKSWith the advent of readily available
9、 supplies of water inside the house, water began to be used to flush wastes down the drain. Water pipes from sinks, lavatories, tubs, showers, water closets (toilets), urinals, and floor drains form a network drained by gravity (Fig. 10-1). In order to preserve the gravity flow, large waste pipes mu
10、st run10C h a p t e rWaste Plumbing50Waste Plumbing51downhill, and normal atmospheric pressure must be maintained throughout the system at all times. Clean- outs are located to facilitate removal of solid wastes from clogged pipes. Cast iron is used for waste plumbing in both small and large buildin
11、gs. Cast iron was invented in Germany in 1562 and was first used in the United States in 1813. It is durable and corrosion resistant. Cast iron is hard to cut, and was formerly joined at its hub joints using molten lead. Today, cast-iron pipes use hubless or bell- and-spigot joints and fittings or a
12、 neoprene (flexible plastic) sleeve. Plastic pipes made of ABS or PVC plastic are light- weight and can be assembled in advance. Copper pipes have been used since ancient times. Some building codes also allow galvanized wrought iron or steel pipes. Engineers size waste plumbing lines according to th
13、eir location in the system and the total number and types of fixtures they serve. Waste piping is laid out as direct and straight as possible to prevent deposit of solids and clogging. Bends are minimized in number and angled gently, without right angles. Horizontal drains should have a 1 : 100 slop
14、e (?1 8?in. per foot) for pipes up to 76 mm (3 in.) in diameter, and a 1:50 slope (?1 4?in. per foot) for pipes larger than 76 mm. These large, sloping drainpipes can gradually drop from a floorthrough the ceiling below and become a problem for the interior designer. Cleanouts are distributed throug
15、hout the sanitary system between fixtures and the outside sewer connec- tion. They are located a maximum of 15 meters (50 ft) apart in branch lines and building drains up to 10 cm (4 in.). On larger lines, they are located a maximum of 30.5 meters (100 ft) apart. Cleanouts are also required at the b
16、ase of each stack, at every change of direction greater than 45 degrees, and at the point where the building drain leaves the building. Wherever a cleanout is located, there must be access for maintenance and room to work, which may create problems for the un- wary interior designer. Fixture drains extend from the trap of a plumbing fixture to the junction with the waste or soil stack. Branch drains connect one or more fixtures to soil or waste stacks. A soil stack is the waste pipe that runs f
