02 water supply

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Pipes have NPT ("National Pipe Thread") standardthreads, which mate with inside threads on elbows,couplers and other fittings.

Galvanized iron (often known simply as "galv" or"iron" in the plumbing trade) is relatively expensive,difficult to work with (due to weight and requirementof a pipe threader), and suffers from a tendency toobstruction due to mineral deposits forming on theinside of the pipe.

It remains common for repair of existing "galv"

systems and to satisfy building code non-combustiblity requirements typically found in hotels,apartment buildings and other commercialapplications. It is also extremely durable.

Generally, copper tubes are soldered directly into copper orbrass fittings, although compression or flare fittings arecommonly used by residential plumbers (Note: the annealingquality of the pipe or tube can affect the performance ofcompression fittings and their ability to "make-up" duringinstallation).

Formerly, concerns with copper supply tubes included thelead used in the (50%tin-50%lead)solder at joints. Somestudies have shown significant "leaching" of the lead into thepotable water stream, particularly after long periods of lowusage, followed by peak demand periods.

In hard water applications, shortly after installation, theinterior of the pipes will be coated with the depositedminerals, which had been dissolved in the water andtherefore the vast majority of exposed lead would beprevented from entering the potable water. Building coderequirements often require lead-free solder for copper andbrass. Building Codes throughout the U.S. require the use ofvirtually "lead-free" (


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Water Pipes and Fittings

Plastic pipe is used in many plumbing applications becauseit's relatively inexpensive, easy to install and impervious tocorrosion. In some locations, plastic pipe is not allowed bycodes for supply piping.

Rigid pipe may be PVC (polyvinyl chloride) for cold water orDWV plumbing, CPVC (chlorinated polyvinyl chloride) for hotand cold water and ABS (acrylonitrile-butadiene-styrene) forDWV piping. Flexible plastic tubing is made from PB(polybutylene) and PE (polyethylene). Plastic pipe is rated for

the pressure it can handle; this rating is stamped on theoutside of the pipe.

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Rigid copper pipe is widely preferred for water supply piping.It's sturdy and durable, resists mineral buildup and can handleboth cold and hot water. Hard supply pipe is sold in threethicknesses: M (thin wall), L (medium wall) and K (thick wall).Most above-ground plumbing is Type M.

Soft copper supply pipe is more expensive than hard copperpipe but is flexible enough to be routed without as manyfittings. Type L (medium wall) is more commonly used thanType M (thick wall) for above-ground applications. Copperpipe may bejoined with permanently soldered fittings orflare/compression fittings that can be disassembled.

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Galvanized iron pipe and fittings were standard for watersupply plumbing before 1960 and are still common. Thegalvanized zinc coating on the outside of this pipe resistsrust and corrosion but insides of pipes clog up withmineral deposits and corrode over time. Water-tightconnections are made with threaded fittings. Larger-diameter galvanized iron pipe is used for vent plumbingin some houses.

To prevent corrosion from electrolysis that occurs whentwo dissimilar metals are joined together, a dielectricunion should be used anywhere copper is connected to

an iron pipe. Cast iron pipe is a strong, durable material used for

drain, waste and vent (DWV) plumbing. Two types arecommon: the older "hub" or "bell-and-spigot" type thatis joined together with lead and oakum and newer "no-hub" or "hubless" fittings that are connected with specialrubber gaskets and stainless steel band clamps.

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House Plumbing A house actually has

several plumbing systems.

Water supply piping bringswater to the house anddistributes it to fixtures andappliances, includingoutdoor sprinklers andirrigation.

Drain and waste plumbingdisposes of used water andwaste.

Vent piping exhausts sewer

gasses and provides properpressure for the drainpipes.

And some homes evenhave pipe systems thatserve specialty needs-swimming pool plumbingand built-in vacuum piping,


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Water Valves and Hose Bibb's A hose bibb, an outdoor faucet, is threaded to receive agarden hose. The type with a wall-attachment flange is called

a sillcock.

The globe valve serves as a shutoff valve that also controls

water pressure. Unlike the gate valve, this shutoff valve can

be used partially open. Angled varieties are also available.

Water meter &water shutoff valve

Water travels under pressure through a system ofpipes to our homes.

The water company uses a water meter to measurehow much water you use (unless your water use isn'ttracked). This meter is often buried in a housing witha removable lid, located in front of the house, near

the street. In cold-winter areas, it may be inside thebasement or crawl space-often placed where themeter reader can check it monthly withoutdisturbing you. The water company delivers water tothe meter through a large pipe called a main, whichoften parallels the street.

A gate valve, used as main shutoff valve, is designed to beused either completely open or closed. As you open the valve,a tapered wedge retracts from the water channel into valve'sbody, allowing water to flow. When closed, the wedge createsa seal. Other valves control the flow of water through parts ofyour supply system. A valve near the house may shut off allwater indoors; another may control all garden water.

A main shutoff valve is often located on each side of the watermeter. The one on the street side is the water company'svalve-the one used to shut off the system when they want to

work on or change your meter. The other one controls waterthat flows to your house. This is your main shutoff; turning itcompletely clockwise will stop all water flowing through yourwater supply system-both indoors and outdoors.

02 water supply

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