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Your home plumbing system will have different types of piping materials for different uses, including freshwater supply, waste drainage, irrigation, gas pipes for appliances, and so on. Which type is used in which application will largely depend on the age of your plumbing system? An older plumbing system may be dominated by cast iron and galvanized iron, while a new home will have plastic pipes of various types used almost exclusively.
Some plastic pipes used in plumbing (such as PVC and CPVC) may also be used in the venting of high-efficiency condensing furnaces. However, this will be an overview of pipe materials for use in plumbing applications. These are the most common types of plumbing piping materials found in homes of different ages, what they are used for, and an overview of how to cut and fasten them together. Here are types of plumbing materials used in piping for waste lines, water supply pipes, and natural gas supply:
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- Cast iron for plumbing waste lines
- PVC (PolyVinyl Chloride) for plumbing waste lines
- Chromed brass for plumbing waste lines
- Chromed copper for water supply lines
- Galvanized iron for water supply lines
- Copper (rigid and flexible) for water supply lines
- CPVC (Chlorinated Poly-Vinyl Chloride) for water supply lines
- PEX (Cross-linked Polyethylene) for water supply lines
- Black iron for gas pipes
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Appearance: Large-diameter heavy metal pipe, dull black with a rough, mottled surface.
Description: High-quality sanitary waste drain pipe that is heavy and deadens the sound of flowing wastewater very well. This pipe is strong and long-lasting but hard to cut—often requiring a special cutting tool with sharp chain cutting wheels. Repairs are often made using plastic PVC piping. Cast iron is rarely used in new construction; instead many use plastic PVC or ABS (acrylonitrile butadiene styrene) pipe.
Prevalent Use: Use for main soil stack waste lines and vent pipes.
Cutting and Fitting: Requires heavy-duty reciprocating saw or a special cutting tool called a cast-iron pipe cutter. Securing cast-iron pipes and fittings together is done using special methods, including lead and oakum in soil pipe joints, hubbed fittings or hubless couplings using pressure bands, and other methods usually unfamiliar to the homeowner.Continue to 3 of 10 below.
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PVC (Poly-Vinyl Chloride)
Appearance: White rigid plastic.
Description: PVC is now the de-facto standard in-home waste line materials. It is a strong, chemical-resistant rigid pipe that is heat resistant and easily cut and fit. It is often used to repair sections of broken cast-iron waste pipe as well as repairs to other drain lines.
Prevalent Use: Use for sanitary waste lines, vent pipes, and drain traps.
Cutting and Fitting: PVC pipe is easily cut with a hacksaw or tubing cutter. The sections are joined together mechanically, using plastic pressure fittings for later removal, or permanently joined using special chemical solvent.
NOTE: You may notice another plastic pipe used in your home plumbing system—a black plastic pipe. This is ABS (Acrylonitrile Butadiene Styrene) and has largely been replaced by PVC in new construction and plumbing repairs, mostly because it degrades when exposed to sunlight. If you have ABS pipe, it is cut and fitted using the same methods as for PVC.Continue to 4 of 10 below.
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Appearance: Bright, shiny chrome-finished pipe of larger diameter (more than one inch).
Description: Chromed brass is often used in lieu of PVC for exposed waste line applications, such as “P” traps or other drain traps where appearance is important.
Prevalent Use: Exposed drains and traps.
Cutting and Fitting: Easily cut with a hacksaw, and joined with slip fittings.Continue to 5 of 10 below.
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Appearance: Bright, shiny chrome finished pipe of smaller diameter (3/8” or less).
Description: Chromed copper pipe is often used where the appearance of exposed water supply lines is important.
Prevalent Use: Exposed water supply lines, such as supply tubing for toilets or pedestal sinks.
Cutting and Fitting: Easily cut with a tubing cutter or hacksaw, and joined with chromed brass compression fittings.Continue to 6 of 10 below.
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Appearance: Dull silver-gray rigid metal pipe.
Description: Galvanized iron pipe was once a popular method of plumbing water supply lines in the home, but it gradually fails due to corrosion and rust. For this reason, it is no longer commonly used and has been largely replaced with copper pipe or PEX plastic pipe. Galvanized iron pipe is difficult to cut and join and not easily fabricated on site by the homeowner. Repairs are usually done by replacing the pipes with copper or PEX.
Prevalent Use: Water supply lines and drain lines in older homes.
Cutting and Fitting: Can be cut using a reciprocating saw or hacksaw. The pipe is joined by using threaded galvanized iron fittings.Continue to 7 of 10 below.
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Copper (Rigid and Flexible)
Appearance: Dull, copper-colored metal pipe.
Description: Copper pipe comes in two types: rigid and flexible. The rigid type comes in several wall thicknesses: K, L, and M. Type M is the one normally used for water supply pipes. Copper has proven itself over the decades to be corrosion resistant and very reliable. Copper is a soft metal and can be easily cut and fabricated. It is also prone to damage, may develop pinholes over time, and can rupture from frozen water in pipes.
Rising costs for copper in recent years have caused PEX and CPVC to be used more frequently. Copper pipe costs as much as three times as much as PEX.
Prevalent Use: Rigid copper pipes are used for longer runs of water supply, and in some cases as waste lines in the home. Flexible copper is used in short runs, for water supply, and for the water supply tubing for refrigerators and dishwashers. Copper may also be used for gas piping.
Cutting and Fitting: Copper pipe is easily cut with a tubing cutter or hacksaw. Sections are joined together with soldered copper connectors or copper compression fittings. The flexible copper pipe may also be terminated by flaring its end and using brass flare fittings.Continue to 8 of 10 below.
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CPVC (Chlorinated Poly Vinyl Chloride)
Appearance: Dull white or cream-colored plastic.
Description: CPVC is an inexpensive rigid plastic that is designed to withstand high pressure and temperature.
Prevalent Use: CPVC is used for hot and cold water supply piping.
Cutting and Fitting: The pipe is easily cut with a tubing cutter or hacksaw. CPVC is joined permanently together using plastic fittings and solvent glue, or with grip fittings where the pipes may need to be disassembled in the future.Continue to 9 of 10 below.
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PEX (Cross-linked Polyethylene)
Appearance: Typically blue (cold water), red (hot water), or white flexible plastic pipe.
Description: PEX is made of cross-linked HDPE (high-density polyethylene) polymer and is an incredible piping material that has been in use since the 1970s. PEX is strong and flexible, withstanding temperatures from below 32 F to 200 F. PEX is corrosion resistant, and unlike copper pipe, it will not develop pinholes. Because PEX is flexible and uses fewer connections and fittings, it is easier and faster to install. The reduced number of required fittings in a PEX system also reduces the possibility of leaks.
PEX has become a favorite of contractors installing new plumbing systems and plumbers making major upgrades to older systems. Increasingly, homeowners are also discovering the merits of PEX pipe.
Prevalent Use: Water supply and radiant heating pipe.
Cutting and Fitting: PEX is cut and fit with specialized fittings and tools.Continue to 10 of 10 below.
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Appearance: Dull black rigid pipe, usually one inch or less in diameter.
Description: Black pipe looks almost exactly like galvanized iron pipe, except it is darker and specifically designed for gas applications.
Prevalent Use: Natural gas or propane supply pipes. It is often used for feeding gas supply to the furnace, boiler, or water heater.
Cutting and Fitting: Can be cut using a reciprocating saw or hacksaw. The pipe is joined using threaded black pipe fittings.