April 4, 2022
While there are many different types of plumbing pipes used in residential homes, this article will focus on the most common water line and sewer line plumbing pipes found in the Triad of North Carolina. Whether you are buying, building or already own a home, it is important to understand and identify the type of plumbing pipes being used. Each pipe has its own set advantages and disadvantages based on its unique chemical structure and composition. Read on to learn more about the different types of plumbing pipes and their uses.
Most Common Types of Water Pipes:
The most common types of water supply lines are PEX, copper, galvanized,CPVC, and polybutylene. However, polybutylene is not up to NC plumbing code and will only be found in existing structures.
PEX, also known as Cross linked polyethylene, is most commonly found in homes built after 1995. It differs from polybutylene in its molecular structure. Because pex is cross linked, it is a stronger, longer lasting pipe.
Identification: PEX pipe has a smooth texture and can be red, blue or white. Red is used for hot water lines, blue is used for cold water lines and white can be used for both hot and cold water lines for a cleaner look. PEX ranges in size for residential application from ¼ inch to 1 inch. Though the most common sizes are ½ , ¾ and 1 inch. Each pipe is labeled with information such as the manufacturer, part or lot number, manufacturing date and other design specifications and ratings.
Advantages: PEX is resistant to corrosion and can handle ground shift better than other more rigid pipes. While PEX is firm enough to handle the water supply for a house, the slight flexibility in PEX pipe makes it easier to use for remodels, re-pipes and new construction.
Disadvantages: PEX is not puncture resistant. When piping in a home’s water lines, it is important to use nail plates over the studs so that a nail doesn’t puncture the pipe creating a leak. PEX pipe is sensitive to UV light and extreme temperatures. However, these disadvantages do not pose a problem because the pipes will be located indoors, insulated in the walls of your home.
Copper pipe is considered to be the old gold standard. It is most commonly found in homes built after 1940. Water quality plays a big role in whether copper pipe is a good fit for your home. With high quality water, copper lines can be very reliable and have a long lifespan. With poor quality of water, the water will leech the mineral from the pipes causing them to become weak.
Identification: Copper is a reddish brown color pipe that has no flexibility. You may notice a green substance built up on the pipe called patina. It is caused by oxidation, a process that occurs from the copper being exposed to water and air causing corrosion over time.
Advantages: Copper is a reliable, long lasting plumbing pipe if you have good water quality.
Disadvantages: Reliability depends on the quality of your home’s water supply. Copper is more prone to corrosion than other pipe options, like PEX. Copper is still a great choice of pipe but can be very expensive, making it impractical in new construction homes.
Galvanized water lines are typically found in homes built before 1985. Galvanized pipe is created by coating steel with zinc. This coating is used to help protect the steel from rusting as quickly. Galvanized pipes were used as an alternative to replace lead pipes.
Identification: Galvanized pipe is a metallic gray color when it is new, but over time the zinc coating will wear off and it will begin to rust causing the pipe to change color.
Advantages: Galvanized pipe was a long lasting affordable choice for its time. Galvanized pipe is puncture resistant.
Disadvantages: As plumbing has advanced, so have the materials. Galvanized pipe has more overall disadvantages than advantages. It tends to corrode, creating small leaks at the joints. When galvanized pipe starts to corrode, it corrodes inward causing lower water pressure and/or discoloration in the water. Galvanized pipe is more difficult to work with due to it being the most prone to corrosion compared to other materials and its age in existing residential homes. Once the galvanized pipe has corroded enough, the water supply will turn a red or brown color from the excess of iron in the pipe.
CPVC stands for Chlorinated polyvinyl chloride. It is commonly found in homes built after 1985 and used by homeowners because you do not need specialized tools to work with it.
Identification: CPVC is most commonly found in a cream color but it is also made in yellow and gray. Similar to PVC, specifications are clearly printed on the pipe. It is made in the same sizes as PEX pipe.
Advantages: CPVC is known to be highly corrosion resistant. CPVC can handle higher temperatures than other pipes.
Disadvantages: Over time, CPVC will start to become brittle. It is not a flexible pipe and will snap when put under too much stress or pressure. The type of glue used to connect CPVC takes longer to set up than other pipes.
Polybutylene pipe is a gray pipe used in homes from the late 1970s to the early 1990s. The molecular structure is linear causing it to be a weak and brittle pipe. We highly recommend a full home repipe if you have this type of pipe in your home. Many insurance companies will not cover claims with polybutylene or will have a surcharge on your premium for antique plumbing. After the amount of damages caused by this pipe, there have been class action lawsuits and it is now against code to use polybutylene.
Most Common Types of Sewer Pipes
The most common types of sewer pipes are ABS, PVC and Cast Iron/Galvanized.
ABS is acrylonitrile butadiene styrene. ABS is most commonly used underground as it can handle cold temperatures but not sunlight.
Identification: ABS is a solid black plastic pipe.
Advantages: ABS doesn’t corrode and is less likely to have build up like cast iron or galvanized pipe. People commonly say the joints are glued together, but it is actually a solvent weld which is a much stronger connection. ABS uses a one step cement to bond the pipe together at its joints.
Disadvantages: ABS is considered to be more flammable than PVC pipe and in certain areas it is only used to make a repair because it is not permitted for new construction.
PVC is the new standard choice for sewer pipes. PVC is most common in homes built in 1985 to present.
Identification: PVC is a white pipe and, just like PEX and CVPC, it has all of the pipe’s specifications printed on it.
Advantages: It is durable, corrosion resistant, less prone to breaks and disjointing underground. PVC is much lighter than cast iron and galvanized pipe making it easier to work with. Like ABS, PVC is connected by a solvent weld. Properly glued joints are less likely to settle or disjoint from things like ground shift.
Disadvantages: PVC takes a two step process of primer and cement to join the pipe together. If not properly primed, the joint can separate causing a leak. PVC is not puncture resistant.
Cast Iron/ Galvanized
Cast iron/ Galvanized sewer lines are most commonly used in commercial applications and in homes built before 1985. Though there are not a lot of pros to using galvanized pipe, it is still a required material to meet code for some applications.
Identification: Cast iron is a metallic pipe that is black in color. It comes in two styles; hub and spigot and no hub. Hub and spigot can be identified by the “bell ends” where the non-hubbed end of the pipe, the spigot, joins to the hub. No hub cast iron can be identified by its lack of hubs making its connections with shielded no hub bands. Galvanized sewer pipe looks very similar to galvanized water pipe but on a larger scale. Galvanized sewer is typically sized as 1 ¼ to 2 inches.
Advantages: These two types of pipe are very puncture resistant. They can be used in place of PVC when a fire retardant material is needed. It can be used between floors of a home to reduce the noise of water flowing through the drain. There are certain situations where code requires the use of metallic pipe over PVC.
Disadvantages: Cast iron and galvanized pipe are prone to corrosion, cracks and breaks. Cast iron pipe will not settle out, but the joints can. When this happens, it creates a belly causing back ups with your sewer. Metallic pipe is also not very chemical resistant and can break down over time from acids going through the drains.