Quick Guide to Plumbing Materials

quick guide to plumbing materials

Quick Reference Guide: Plumbing Materials

Drinking Water Plumbing Materials

Drain-Waste-Vent Plumbing Materials

Drinking Water Plumbing Materials


About PEX plumbing:

PEX is one of the most commonly used water distribution plumbing materials today.  Plumbers and installers prefer PEX because of its flexibility, affordability, and ease of installation.  PEX does not corrode and is less likely to burst during freeze events than metal pipes.  PEX has proven to be a durable and reliable material as long it is installed correctly (an exception is the Q-PEX fittings)

Uponor or Wirsbo manufactures Type A PEX.  Type A has better flexibility and fewer flow restriction problems at the fittings than Type B.  This type is also more expensive and less commonly available in our area.

Type B PEX manufactured by Zurn is more commonly used and available in our area.

Potential Issues with PEX plumbing:

Dezincification of Brass Fittings (the 1990s-2013):

Dezincification concerns the connectors or fittings and not the pipes themselves.  Between the 1990s and 2013, some manufacturers produced sub-standard brass fittings known for dezincification, corrosion, and leaks.  Zurn, one of the fitting manufacturers, settled a class action lawsuit in 2013– their brass fittings are labeled ‘Q-PEX’ or with the number ‘F-1807’.  As a home inspector, I can confirm that this is a prevalent issue, and several of my clients have had to replace their fittings and/or most of their pipes (sometimes after only 10-20 years).  

Flow Restriction at PEX Fittings: 

Because Type B (Zurn) fittings utilize insert type fittings, they can noticeably reduce the flow and should be up-sized as needed.

Incorrect PEX Transition Fittings:

Special fittings are needed when PEX is connected to other materials, such as Polybutylene or copper.  It is common to find leaks where the incorrect fitting is used – see Transition Fittings for more information.

PEX and VOCs: 

Like all plastic piping, evidence suggests that PEX leaches VOCs into the drinking water supply – especially during the first 3-5 years of installation.  


About Copper drinking water plumbing:

Copper piping is still commonly used today and is known for its reliability and longevity.  Copper can handle high temperatures and may be the longest-lasting of all plumbing distribution types.  Copper piping typically requires more specialized tools and skills than PEX to install or repair.  Special fittings, like SharkBite, may allow a homeowner to do their repairs; however best practice is to hire a licensed plumber when repairing or replacing copper piping.

Potential issues with Copper drinking water plumbing:


Copper is prone to damage from highly acidic water- most public water providers take steps to prevent acidic water; however, homes with private wells or springs may have acidic water.  Copper piping is made for different applications and has various wall thicknesses (Type K, L & M)- thinner piping (like Type M) is more prone to acidification and leaks over time.


Copper is more prone to freezing/bursting than PEX which is why steps should be taken to insulate or protect copper piping in unheated areas in regions that have freezing temperatures.

Lead Solder:

Lead solder was commonly used with copper in cities and homes built before 1986.  The lead can leach into the drinking water supply, especially when the water is acidic.  Lead is a known health hazard.


About CPVC plumbing:

CPVC was initially marketed as a product that is easy to install and can withstand hot temperatures up to 200F (93C) as opposed to 140F (60C) for PVC (although residential water heaters should not be set above 120F).  

Potential issues with CPVC plumbing:

Not Resistant to Some Chemicals: 

Studies have shown that CPVC is vulnerable to hydrocarbons (present in many products we may use in the kitchen or bathroom) and will become brittle after regular exposure.


Compared to PEX or PVC, CPVC is more vulnerable to freezing temperatures.

Emits VOCs: 

Like all plastic piping, evidence suggests that CPVC leaches VOCs into the drinking water supply – especially during the first 3-5 years of installation.  


About PVC drinking water plumbing:

PVC has proven to be a very reliable and durable material when properly installed.  PVC is still very commonly used for water distribution. However, PEX has become increasingly popular because of its flexibility, price, and ease of installation.

Potential issues with PVC drinking water plumbing:

Like all plastic piping, evidence suggests that PVC leaches VOCs into the drinking water supply – especially during the first 3-5 years of installation.  

Discontinued Drinking Water Plumbing Materials

Galvanized (1880s-1960s)

Issues with Galvanized water supply and distribution plumbing:

Galvanized pipes are known for de-zincification, corrosion, and leaks.  Corrosion inside older galvanized pipes can restrict the flow or even obstruct the water pressure- this is very common.  Galvanized pipes have not been installed since around 1960. They have about a 50-year life expectancy which means all galvanized distribution pipes in older homes are now beyond their life expectancy and are overdue for replacement.  Metals, including Zinc and Lead, can leach into the drinking water from galvanized pipes.  Except for occasional short sections at plumbing fixtures and appliances, galvanized pipes are no longer used for distribution plumbing because of these known issues.

Underground Galvanized pipes ($$$$)

When the underground service pipe (from the well or municipality) is galvanized, this could present a potentially complex and expensive project to the homeowner that will require trenching and navigating through hard surfaces, landscaping, additions, etc…

Galvanized Distribution Pipes ($$$)

Replacing galvanized distribution pipes in unfinished crawl spaces and basements may be straightforward, but less accessible areas like finished walls and ceilings will increase replacement costs.  In some cases, hidden sections of galvanized plumbing are still present in homes.

Short Sections of Galvanized Pipes ($)

Short sections of galvanized pipes are still used today near appliances and fixtures (stub-outs). These short sections of galvanized pipe can discolor the water and leach metals into the drinking water.  The best practice is to have the short sections of pipes replaced. 

Polybutylene (1978-1997)

Issues with Polybutylene plumbing:

There was a class action lawsuit in 1995 due to leaks and damaged pipes, and now Polybutylene is no longer installed in homes.

Becomes Brittle (city water):

Polybutylene pipes are subject to damage from chemicals over time, mainly from chlorine used to treat municipal water.  There may be less of a concern if a well supplies the water.  The chemical reaction occurs inside the pipe, and therefore the extent of the damage is hidden or difficult to determine.  Leaks or failure may develop suddenly and without warning.

Incorrect Polybutylene Transition fittings:

Because polybutylene is similar in size to PEX, many homeowners and unlicensed professionals (and some licensed ones) have used the incorrect type of fitting when transitioning from one material to another.  It should always be verified that the correct Polybutylene to PEX fitting is used (or other material) to prevent leaks over the long-term

Polybutylene and VOCs

Like all plastic piping, evidence suggests that PVC leaches VOCs into the drinking water supply – especially during the first 3-5 years of installation. 

Transition Fittings

Plumbing materials have different inside and outside diameters, so the correct fitting should always be used when one material type is connected.  Incorrect fittings can result in leaks.  Companies like Sharkbite and Zurn use a color band to help installers match the fitting with the correct material.  See the color code below to verify that the correct fittings were used:

Correct Color Codes for PEX to Polybutylene fitting:

Tan color: Polybutylene
Black: PEX

Correct Color Codes for SHARKBITE fittings:

Grey: Polybutylene
White: PVC

Tan: CPVC, PEX, copper

Dis-similar metal connections:

It is common to see di-similar metal connections at water heaters, well heads, and well pressure system equipment.  When incompatible metals touch each other, they will corrode over the long term.  It is important to use compatible materials, or when connecting dis-similar metals, di-electric fittings should be used to isolate the materials from each other


di electric union
Di electric union isolate dis-similar metals from each other and prevent corrosion and leaks over the long term


Best Practices for Drinking Water Plumbing

Typical Sizes:

Water service supply (from municipality or well) = 1″ (typically)
Water Distribution = 1/2″ (typically)

Minimum Support Spacing for 1″ diameter or smaller diameter pipes:

PEX (1″ or less) = 32″
PVC= 36″
CPVC= 36″
Copper= 4′ and within 1′ of a change of direction

Water supply pipes should be installed 1.5″ behind the face of the stud or otherwise protected with a shield plate to prevent leaks and flooding.  Underground water supply pipes should be buried below the frost line (16″ in our area) with a 14 gauge ‘tracer’ line to help locate the pipe.  Water supply pipes should be rated for household use that can withstand a pressure of 80psi or more and temperatures of 120F or more.

Drain-Waste-Vent Plumbing Materials


PVC is the most commonly used drain line material within residences and has proven to be a durable material over time.  PVC is more flexible and muffles sound better, which is why it is used within the home more than ABS.

Types of PVC DWV:

Schedule 40 (Most residential applications)
Schedule 80 (Commercial or Industrial applications)
Schedule PR160 (Landscaping – French drains and downspout sub-surface drains)


Similar to PVC, ABS is still commonly used today and has proven to be a durable material over time.  ABS is slightly more robust and resists impact better than PVC, which is why it is commonly used in underground applications.

Vitrified Clay (terra cotta)

Vitrified clay is a material that has been used for millennia and is still commonly used today for underground applications.  Vitrified clay is acid, corrosion, and abrasion-resistant.

Potential Issues with Vitrified Clay Drain Lines

Vitrified clay is more difficult to install and repair than PVC/ABS.  Older Vitrified clay materials used in sewer line applications are prone to leak at connections, have low tensile strength, and are vulnerable to root damage.

Cast Iron

Cast iron was the best of the older materials and is known for its durability.  Cast iron drain-waste-vent pipes have a service life of between 50 and 100 years and, in some applications, are still used today. 

Potential Issues with Cast Iron

Since Cast Iron drain lines have not been installed since around 1975, much is older and beyond the expected service life. Acidic sewage and humid environments in crawl spaces can cause corrosion and plumbing leaks over the long term. Cast iron is more difficult to repair/replace than PVC/ABS.  Specialized tools and techniques are often required for a successful repair.

Copper DWV

Copper drain pipes are sometimes seen in homes built before 1970.  Copper DWV are still allowed but are generally no longer installed because of the expense and corrosion/longevity issues.

Issues with Copper Drain Lines

Copper drain lines are prone to acidic corrosion caused by sewage.  Copper drain lines still in use are beyond their service life and should be replaced soon to prevent leaks.

Discontinued Drain-Waste-Vent Plumbing Materials


Galvanized DWV

Galvanized drain lines have a 50-year life expectancy.  Galvanized drain lines for residential applications typically have not been installed since the 1960s

Issues with Galvanized Drain Lines

Most, if not all, galvanized drain lines present in homes are now beyond their expected service life and should be replaced soon. Galvanized drain lines are prone to corrosion from the inside (dezincification) and can cause leaks, floods, water damage, and failure.

Lead DWV

Commonly used up until the 1950s, lead was used because it was a corrosion-resistant and malleable material. Lead pipes were banned by congress in 1986 (lead drain lines were allowed to stay in place).  Still seen today in homes but typically in drain lines only (lead water supply pipes are much more of a concern).

Potential Issues with Lead Drain Lines

Lead is a known hazard and is toxic to the touch.  Lead can cause lead poisoning if not handled carefully.

Orangeburg DWV

Orangeburg pipes were typically used for drain line systems between 1950 and 1970.

Issues with Orangeburg Drain Lines

Orangeburg pipes were made from wood pulp and tar, and Orangeburg pipes are known for their lack of strength and for their propensity to compress/deteriorate and fail catastrophically.  Orangeburg is no longer manufactured or considered an acceptable plumbing material.  Any Orangeburg pipes that are still in use today are now beyond their expected service life and should be replaced soon to prevent leaks, water damage, and sewer issues.

Best Practices for Drain-Waste-Vent Plumbing

Waste line pipes should be gradually sloped downward to ensure waste (typically 1/4″ per foot or 1/8″ for 3″ and larger pipes).  PVC and ABS drain line pipes should be supported every 4′.  Every house should have at least one vent exit through the roof.  Every plumbing fixture should have a trap and a venting system to help prevent the escape of sewer gases and ensure proper drainage.

Typical Sizes of Plumbing Drain Lines

Main Waste Line = 3″ for smaller homes and 4″ for larger
Toilet = 3″ or 4″
Shower Waste Line = 2″
Sink = 1-1/4″ to 1-1/2″

Asheville and WNC Plumbing Inspectors

Builder Buddy is your resource for Plumbing Inspections in the Asheville area.  We also provide Well Inspections, Water Testing, Septic Inspections, and more.  Schedule online or call with questions.

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