Installing or replacing water supply pipes can be a challenge. Choosing which type of piping material, PEX vs copper pipe, just adds another drop in the preverbal bucket. Both have decades of use and hundreds of thousands of homeowners enjoy the benefits or curse the deficiencies of each.
Both copper and PEX are used as water delivery pipes. PEX is more flexible and much cheaper than copper and has been rapidly overtaking copper piping for those reasons. However, PEX is also a petroleum product and can leach toxic contaminants into drinking water. Copper, on the other hand, is an antimicrobial mineral and is considered much safer for potable water transportation.
In this guide, we’ll explore the differences between PEX and copper plumbing supply lines, explain what each is, and the different types of each available. We’ll also look at the advantages and disadvantages, when PEX shouldn’t be used, and even compare both with PVC piping. Our goal is to provide you with a complete guide, so you can make the best decision for your project.
PEX vs Copper Pipe: Key Points
The table below provides a quick comparison of the key points in the PEX versus copper pipe argument and should assist in any decision on which to use for your project.
What Is a PEX Pipe?
PEX pipe or tubing was developed by Thomas Engel, a German scientist, in 1968. It was initially formulated and invented in the 1930s, but processing wasn’t feasible, so it was shelved. Its potential applications for continuous piping or tubing, coupled with its durability and light weight, make it ideal for numerous applications. By the mid, to late 80s PEX tubing was widely in use in Europe for plumbing, radiant heating applications, and other liquid transfer uses.
PEX didn’t catch on in North America as quickly, though, since the chlorine used to purify water in many regions caused the plastic to deteriorate. It was, however, used in other applications such as radiant heating systems for floors. After some work to make the plastic less susceptible to damage by chlorine, PEX used for water supply flooded into residential and commercial structures in North America too.
PEX tubing or pipe is made of flexible cross-linked polyethylene (PE) thermoplastic. The flexibility means it is easier to install, can be fed around corners, through holes, and snaked through other pipes with minimal connections, so less risk of leaks. It also means that it can expand and contract, minimizing the potential for cracking in sub-zero temperatures and causing leaks. So, it is resistant to freezing and corrosion, making it a great alternative to different types of metal piping.
What Is PEX Pipe Made Of?
PEX pipe or tubing is made of high-density polyethylene (HDPE) using the ‘Engel Method’ which uses very high temperatures to cross-link the ethylene molecule chains. It is an extruded cross-linked thermoplastic polyethylene – poly refers to polymers or chains of ethylene molecules. It is commonly known as PEX but is also referred to as XLPE or XPE, referencing the cross-linked (X or XL) of the poly (P) ethylene (E). The cross-linked molecules make PEX different and more enhanced than other thermoplastic polyethylene materials.
Comparatively, PEX is more chemically stable so resistant to dissolution, has improved resistance to abrasion, is less brittle, more flexible, has greater tensile, shear, and impact strengths, and better low-temperature properties than other PE materials. PEX doesn’t melt like other thermoplastic polyethylene (PE) and can handle short periods up to 248°F under loads and up to 482°F without loads.
Types of PEX Pipe
There are four different types of PEX pipe. They differ due to additives, how they are manufactured, and the resulting attributes. There are also dozens of different brands on the market. The different types all begin with high-density polyethylene (HDPE) but involve different manufacturing processes.
The most common types are PEX A, PEX B, PEX C, and PEX-AL-PEX. The letters identify different additives or manufacturing processes, not the quality or grade of PEX. The different types all meet the same basic standards and comply with ASTM F876, ASTM F877, and SDR9 standards.
PEX pipe or tubing is available in 10’ lengths or rolls up to 500’. Different types come in different colors to make it easier to identify what flows through them. Typically, they come in blue for cold water, red for hot, or gray or white for either hot or cold.
PEX A is manufactured using HDPE with peroxide being added prior to the extruding process. The ‘Engel Method’ is used to ensure 70% or more of the ethylene polymers are crosslinked to meet ASTM burst pressure standards. It is the most flexible, supplest, and bendable, plus crack and kink-resistant type of PEX. PEX A has the lowest density and best thermal memory, so it can expand and return to its original size. Making it the best for environments where freeze-thaw is a concern.
PEX B passes through a silane steam process after it is extruded into tubing, so it is moisture-cured. It is at least 65% crosslinked polymers to meet burst pressure standards. PEX B is the most resistant to oxidation and chlorine, doesn’t require an expansion tool for joints, and is less expensive than PEX A. It is more rigid than PEX A, so doesn’t bend well or handle freezing temperatures.
PEX C is exposed to an electron beam during the manufacturing process to produce the crosslinked ethylene polymers. To meet ASTM F876 burst pressure standards, it must be 65% crosslinked polymers. It is the least expensive PEX and is vulnerable to kinking and cracking, so is more commonly used for short connections or repairs. It is the stiffest and most difficult to work with.
PEX-AL-PEX is manufactured with a layer of aluminum between two PEX layers. This means that it will retain its shape once bent and also is less likely to sag, so fasteners aren’t required every couple of feet. The aluminum also acts as an oxygen barrier, preventing oxygen molecules from mixing with whatever is flowing through the pipes. PEX-AL-PEX is the most expensive type of PEX tubing and is commonly used in radiant heating systems.
Where Is PEX Not Allowed?
PEX has been used in North America for the past two decades and even longer in Europe. It has both residential, commercial, and industrial uses that range from domestic water supply lines, radiant heating and cooling systems, sewage and slurry pipes, insulation for high voltage cables, and even offshore oil and natural gas use.
Even though PEX is widely used for its flexibility, durability, ease of use, availability, and budget-friendliness, there are places it is not recommended or is even banned. There are some industrial, commercial, and residential areas where PEX is not allowed, and some localized Building Codes have restrictions too.
Prior to 2010 PEX was banned in California but has since been allowed and then disallowed numerous times due to legal action over the handling of an Environmental Impact Review on the material. There have also been multiple tests and studies by third-party that have found PEX to be safe for human use applications. So, if hoping to use PEX in California, check the current status first.
In most jurisdictions, PEX is used for residential, commercial, educational, medical, and some industrial applications or structures. Connecting PEX directly to a water heater or other heat source isn’t recommended or acceptable due to its melting point. It also shouldn’t be used in exposed locations where UV rays can deteriorate the material or rodents can damage the tubing. Many building codes that permit the use of PEX for water delivery piping require it to be flushed prior to human consumption.
Other use restrictions applied to PEX include Flame Spread Rate (FSR) and Seismic Design Category (SDC) – ASCE 7-05. PEX has an FSR of 25 and SCD close to 50, which are both considered high. These high values make PEX unacceptable for use in many high-rise buildings and industrial complexes. Additionally, some forms of PEX piping used for industrial applications are known to contain BPA, which becomes a health hazard when exposed to flame.
What Is Copper Piping?
Copper piping was used by the ancient Egyptians and has been the primary water distribution method in North America since the early 1960s. It is manufactured to be soft and bendable or hard and rigid for different applications. Copper piping or tubing is made from naturally occurring copper ore.
The raw material is smelted or heated in large furnaces to more than 2400F, causing it to liquefy and separate from impurities. The pure molten copper is then poured into pipe-shaped molds or castings to fabricate it into pipe. Once cooled, it is removed from the casting, resized or cut into different lengths, and then cleaned. The piping is used to transport different fluids and gasses in a variety of residential, commercial, and industrial applications. Since copper pipe is pure, it is also recyclable.
What Are Copper Pipes Used For?
Copper pipe is strong, easy to solder together, resistant to corrosion, a very good thermal conductor, and comes in both bendable and rigid piping. It is also less expensive and more common than other metals with similar abilities or attributes. As a result, it has numerous uses in industrial, commercial, and residential infrastructures, appliances, and machinery.
Copper piping is used to move different types of liquids and gasses in a variety of applications. It is commonly used to transport cold and hot water within plumbing systems, move refrigerant within cooling systems, refrigerators, and freezers, and even oils and other fluids and gasses in different heating plants.
Types of Copper Pipe
There are four types of copper pipe commonly used to move liquids and gasses in residential, commercial, and industrial operations. The pipes are used for plumbing systems to deliver water and remove wastewater, in heating, cooling, and ventilation or HVAC systems, or to distribute natural gas and oil.
The different types of piping are identified by a K, L, M, or DMW based on the thickness of the pipe wall. Each type is color-coded with printed text on the outside for easier identification. The pipe’s wall thickness affects and determines its use, pressure rating, durability, and price.
Type K is color-coded green and has the thickest walls – 0.049” for 1/2” piping and 0.065” for 3/4” pipe. The wall thickness makes it more durable but also more difficult to use, and more costly. It is commonly used underground for water mains since it is more durable and longer-lasting, so requires less maintenance. It is also used in commercial and industrial plumbing, fire sprinkler systems, and heating, ventilation, and cooling systems.
Type L has blue color-coding that indicates the walls are not as thick – 3/4″ piping has a wall thickness of 0.045”. It is still very durable and is often used where hard water exists, plus it is typically used to replace or repair other copper pipes that haven’t stood the test of time and use. It is used for interior water supply lines, fire sprinkler systems, and heating and cooling systems. It is the most commonly used copper piping type as it can be used underground, inside and outside a structure, and comes in rigid pipe and flexible rolls of tubing.
Type M is color-coded red to indicate wall thicknesses are thinner but still thick enough to withstand most water delivery system requirements – 3/4″ pipe will have 0.032” thick walls. The thinner construction makes it lighter and less expensive. Available in rigid tubing or flexible rolls, it is most commonly used for interior domestic water supply lines where water pressure and waterborne chemicals aren’t a concern.
Type DWV or drain, waste, and vent piping is color-coded yellow. It is not used for potable or pressurized (rated for 15 PSI) water delivery and comes in pipe diameters of 1-1/4” and larger – 1-1/4” pipe has a 0.04” wall thickness. DWV is commonly found in older homes as drains, vents, or wastewater piping, whereas newer homes typically use less expensive PVC piping instead.
What Is the Difference Between PEX Pipe and Copper?
Selecting the best pipe for your use usually depends on what it is made of and for, ease of installation, quality, and how long it will last. Comparing the different products often makes it easier to choose too.
Durability is a key argument in which type of piping to use. Both copper and PEX are durable depending on the situation. PEX is less susceptible to corrosion by hard water, waterborne chemicals, or electrolysis which can cause copper piping to pit or deteriorate and leak over time. Plus, PEX will expand when cold and return to its original shape as it warms, making it better for seasonally occupied dwellings.
Copper doesn’t deteriorate when exposed to UV rays but PEX will, so it isn’t ideal for exposed or lighted locations. Copper piping is hard and won’t be damaged by rodents gnawing on it while PEX will. Additionally, PEX piping is semi-permeable, so liquid vapor can permeate the pipe and contaminate the potable water flowing through it. This is a key reason why copper pipe is considered more durable and is used both underground and above it.
Copper pipe’s life span depends on water chemistry, water flow pressure, electrical grounding of the system, and the quality of the installation. Taking all that into consideration, copper piping has been installed in many homes since the 1940s and is still going strong. Plus, copper piping used by the ancient Egyptians is still intact, although not in use, so its life span is potentially much longer than the 75 years of modern use.
The life span of PEX is still an open question since it’s only been in use since the 1980s. However, the current consensus is that it will last 50 years before needing to be replaced. With time, though, its lifespan may prove to be much longer. We’ll just have to wait and see.
The flow rate is the amount of water or other liquid that can move through a length of piping in a specified time. The rate is typically measured in gpm (gallons per minute) or lpm (liters per minute). A 90° elbow will restrict flow rate more than a 90° curve, especially in high flow situations but only slightly in low flow ones. Pipe diameter also affects flow rate, and PEX has a slightly smaller inside diameter than copper pipe of the same outside diameter.
A fixture flow rate study by The NAHB Research Center compared the flow rate through matching 60’ and 100’ trunk and branch piping systems of PEX and copper using similar diameter piping. The tests were carried out using 40, 60, and 80 psi source pressures for greater comparison. The study concluded that the flow rate was basically the same.
Water freezing in pipes isn’t the best situation regardless of which type of plumbing pipe is used. PEX can withstand freeze-thaw better than copper piping, especially if there’s water in the lines. The PEX piping will expand to accommodate water freezing, and then return to its normal size when it thaws. Copper piping, however, will either rupture or blow a solder joint if water freezes in it, which can cause significant problems when the temperature goes above freezing.
PEX piping is lighter and easier to install than copper and doesn’t require soldering or a lot of tools. It is more flexible, making it easier to manage longer runs without joints, so less chance of leakage. Plus, it can be pressure tested with air to check for leaks prior to connecting to a water source. However, PEX is less rigid than copper and requires more frequent support brackets or clips.
Health & Product Safety
Potable water delivery pipes need to be as safe as possible to ensure the health and safety of those drinking water from them. Copper has a long history of use while PEX has been rapidly introduced into household use in North America. California continues to hold out against PEX, while some smaller jurisdictions place varying restrictions on its use. One complaint about PEX has been that it may affect the smell or taste of the water.
There are more than 70 PEX brands in use, making research difficult. However, studies have identified more than 150 contaminants that raise concerns. A 2021 study of 8 brands identified 62 different contaminants leached into the drinking water, 50% of which are considered toxic. The studies, though, didn’t assess the different fittings that may be used, which may or may not increase the concern. Additionally, PEX may be susceptible to bacteria and microorganisms which can pose a health risk.
Copper pipe has had numerous studies performed on it and is considered safe. An exception is those with ‘Wilson’s Disease’ which can cause a sensitivity to copper consumption. The type of solder has been a concern periodically, but modern solder is considered safe. It is, however, recommended to run the water for 30 to 60 seconds if it has been sitting for six or more hours.
Copper is a common earth mineral that needs to be extracted from the ground, heated or smelted to a pure state, and then cast into a pipe shape. All processes take a great deal of energy, however, copper pipe is 100% recyclable, so highly sustainable. The use of copper piping is considered supportive of green energy provisions and sustainable home construction.
PEX is made from polyethylene glycol, a polyether compound, that is derived from petroleum. In other words, it is a modified natural-gas product or an oil-based product. It too must be extracted from the ground, transported to a refinery, distilled, and then chemically and mechanically manipulated to produce PEX. So, claims that it is more sustainable than copper are questionable, especially as PEX currently isn’t recyclable.
The cost of copper pipe fluctuates some but currently ranges between $2 and $9 a linear foot depending on the diameter and type. Joints, elbows, and other fittings add to that cost too, as do solder, paste, and other tools. Plus, labor is also a big cost as some regions require a qualified plumber or pipefitter to oversee or perform the installation. The cost of PEX is about 60% less than equivalent copper pipe, so between $0.50 and $3 a linear foot. However, installation charges by professionals are often similar.
Pros and Cons of PEX vs Copper
The pros and cons of PEX vs copper piping or tubing often depend on use, quality of installation, and individual experiences. Some may see PEX’s flexibility as a positive as it is bendable, while others may view it as a negative since it means more supports or fasteners are required. Copper piping is more expensive, but has a longer lifespan, making its selection more of a budget issue. The more you know, the easier it will be for you to choose. Here are some pros and cons to check out.
PEX Pipe Advantages and Disadvantages
- DIY friendly
- Longer runs, fewer connections, less risk of leaks
- PEX is durable
- Expand and return to its original size and shape
- Less risk of cracking or bursting during freeze-thaw action
- Resistant to corrosion and mineral buildup
- Easy to install
- Can’t connect directly to heat sources like radiators or hot water tanks
- Deteriorates when exposed to UV light, including indoor lighting
- Not recommended for use outdoors or underground
- Potential health risks
- Currently not recyclable
- Require special fittings
- Warranty issues
Copper Pipes Pros and Cons
- Longer lasting
- Copper is antimicrobial for safer water
- DIY possible
- Rigid so requires fewer support brackets
- It can be used indoors or out, above ground or under it
- Resistant to heat or flame
- Pitting, corrosion, and scaling
- Typically require a trained professional to install or repair
- Not flexible, so requires elbows and joint fittings
- Greater risk of damage by freeze-thaw action
- Possible metallic taste if water has sat in pipes for long periods
PEX vs Copper vs PVC
PEX and copper are typically used today for water distribution within a home while PVC and DWV copper pipes are used for drainage and venting. Copper has a longer life span than PVC, which in turn can outlast PEX. PEX is more flexible than the other two options, but can’t be exposed to UV rays or used outside. Both PVC and copper can be used outdoors and aren’t affected by UV rays, but can rupture if water freezes in them. However, PVC shouldn’t be left exposed outdoors as it can crack over time.
PVC (Poly-Vinyl Chloride) has been in municipal use underground since the 1930s for both potable water delivery and sewage pipes, and many are still in use today. Currently, PVC that meets the Schedule 40 rating can be used for water distribution, sewage movement, drain and vent pipes, and even irrigation under most building codes. PVC is DIY friendly but often requires professional installation within local codes.
Is PEX Better Than Copper for Your Home?
Both PEX and copper piping are viable water supply line choices. PEX is less expensive, easier and faster to install, flexible, can withstand freeze-thaw conditions, and is DIY friendly, but should only be used for interior use. Copper is more durable, sturdier, handles higher temperatures, is longer lasting, and can be used inside, outside, and underground. Copper is also antimicrobial by nature, so kills bacteria on contact, is DIY possible, but is much more expensive.
With all those positives, PEX looks like a sure winner. Unfortunately, PEX is a petroleum product and contains numerous contaminants – many of which are considered toxic – which can leach into the water supply, plus, it can’t be directly connected to a heat source. Copper, on the other hand, may scale up, pit, or erode due to waterborne chemicals. Additionally, copper is 100% recyclable while PEX currently can’t be recycled. The choice of which is better for your home comes down to cost and ease of installation versus longevity and health. The decision is yours to make.