Informational Guide

What Is Pex Plumbing?

This guide will tell you everything you need to know about PEX piping and ultimately how it can make plumbing easier.

by Matt Moran

DIY plumbing is becoming increasingly common. Doing it yourself lets you save money and time, and prevents any reliance on busy professional plumbers. DIY plumbing has become more accessible because modern materials are now readily available.

Traditional piping was made from copper or galvanized metal. These materials are difficult to work with, especially for an amateur, and make plumbing difficult. PEX offers a great alternative.

What is PEX plumbing? PEX is much easier for DIY plumbing. This guide will give you all the information you need to know about PEX, the pros and cons, and ultimately how it can make plumbing easier. 

PEX is short for polyethylene cross linked tubing. Polyethylene bonds create a chemical structure that is superior to most plastics because of its flexibility and durability. Traditional piping would be made from copper or a galvanized metal. PEX offers a modern alternative with a material that’s more affordable and much easier to handle.

PEX offers a number of advantages that are explained further down in this article, but generally, it's just more flexible. It can be bent or twisted, which for a DIY plumber is great because it means you don’t need to be quite as rigid with your measurements. You can also get a variety of different colors to help you codify your plumbing.

There are three main types of PEX pipe:

1. Non-Oxygen Barrier Pex

Non-oxygen barrier PEX is simply PEX without any kind of oxygen. This is used for potable (safe to drink) water. There are two grades of non-oxygen barrier PEX to choose from, each with slightly different qualities:

  • PEX A
    this is extremely resistant to freezing and is really flexible. This is commonly used in kitchens and bathrooms, anywhere you might have drinking water.
  • PEX B
    this PEX piping is of slightly lower quality and is less flexible. It isn’t as resistant to freezing either.

Non-oxygen barrier PEX is only really suitable for indoor use, though you can purchase an outdoor sleeve to help protect against the elements. This type of PEX piping typically comes in red, white, or blue and can be anywhere from ¼ to 3 inches in diameter.

2. Oxygen Barrier Pex

Oxygen is what causes pipes and water systems to rust, and this PEX helps to prevent that from happening. Oxygen Barrier PEX is used in your heating systems which can suffer from corrosion, and just like with Non-Oxygen PEX, there are two grades available. Oxygen Barrier Pex is typically ½ inch in diameter, but you can get some variation to fit different systems.

3. Aluminum Barrier Pex

Aluminum Barrier PEX has a layer of PEX, a layer of aluminum, and another layer of PEX. This sort of 'aluminum sandwich' is useful because it means that the PEX holds its shape once it’s bent into position without any need to secure it. It offers an oxygen barrier and is well suited for high or low temperatures because of its low expansion rate.

What Is Pex Plumbing?

Different Pex Plumbing Pipe Applications

Water Supply Lines Or Portable Distribution Systems

Water supply lines carry the water from the mainline into your home. Non-oxygen barrier PEX is perfect for this and allows you to access safe drinking water.

Radiant Floor Heating Applications

PEX plumbing is perfect for floor heating because it won’t expand or contract as it heats or cools. Radiant floor heating is expensive to run (it can cost up to $6 per square foot) so having more affordable plumbing is a real plus.

Heat Transfer Applications

Similar to the above, PEX won't expand or contract, so it works well with heat transfer applications.

Water Distribution For Hot Water Applications

PEX is often used with your water heaters to allow hot water to flow through various applications.

Residential Fire/Sprinkler Systems

PEX doesn’t corrode or rust when exposed to high-pressure water, making it perfect for sprinkler systems. The durability means you won’t need to replace the copper piping as often too.

Different Pex Plumbing Pipe Applications

Advantages & Disadvantages Of PEX Plumbing

Why Is PEX Plumbing Good? (Pros)

Why Is PEX Plumbing Bad? (Cons)

Flexibility
PEX is much more flexible than traditional piping and can bend up to 90 degrees. This makes it much easier to use, especially for amateurs.

Risk of Leaching
PEX is made from plastic, and there is a risk that chemicals can leach into your water supply. Research is still ongoing, but copper doesn't have this problem.

Durability
The polyethylene bonding is durable, and there's no risk of rust or corrosion.

Vulnerable to rodents
PEX is more vulnerable because mice or rats can chew right through it.

Affordability
PEX can be up to 70% cheaper than copper piping. Copper is also subject to market variation depending on supply.

Risk of chemical damage
PEX is more susceptible to chemical damage. If any rogue chemicals enter your water supply, it can ruin your pipes.

Colour Coding
PEX piping is available in a range of colors, so you can color code your plumbing in a really user-friendly way.

Sensitive to UV
PEX is sensitive to light, particularly sunlight, and prolonged exposure outdoors can damage the material.

Easy to join
PEX piping can be installed using push-to-fit connectors. This is perfect for amateurs because you don’t need any specialized equipment or tools.

Semi-permeable
PEX piping is semi-permeable which means small amounts of liquid can enter your pipes. This has the potential to contaminate your water supply.

Heat Resistance
PEX piping is more resistant to high or low temperatures and won’t expand or contract based on the conditions

Cell

Quieter
Water flows through a PEX pipe much more quietly than traditional copper.

Cell

Acid-resistant
PEX is completely acid resistant, so whatever type of water you have in your area won’t damage the plumbing.

Cell

How To Join & Connect Pex Pipes

One of the main advantages of PEX is how easy it can be connected. These are the primary methods for this:

Copper Crimping

Crimping is really easy, and any amateur can do it. You simply need to attach a copper ring to the end of the PEX, connect it to the attachment, and use a crimping tool (or cinch) to bend the PEX around the metal. You will need a crimping tool to do this effectively.

Expansion Connections

An expansion connection involves using a special tool to expand the diameter of the PEX pipe. You can then slip it over the connection, and it will revert back to its original size, making a watertight seal over the pipe.

Stainless Steel Clamps

This method is often referred to as SSC and involves using stainless steel clamps on the ends of the PEX pipe. This is then connected, and you can use a ratchet tool to compress the clamp and the pipe over the connection, so it's watertight.

Compression Fittings

For this method, you need to fit a brass nut over the end of the tube along with a compression ring. You then need to insert a brass pipe into the PEX tube before you attach the PEX to the connection. You then need to tighten the nut over the fitting.

Push-Fit Connections

Push-fit connections are the easiest and most popular way to fit a PEX pipe. You don’t need any special equipment; you just need a special connection which literally grabs the PEX pipe and holds it securely.


Pex Plumbing Residential Design & Layout

Trunk-And-Branch Systems

Trunk and branch systems involve one large diameter (typically ¾ inches) ‘trunk’ lines transporting water around your home. Several smaller ‘branch’ PEX pipes are then attached to these to transport the water to various applications.

This system is really effective but uses a lot of water. It’s also more complicated to install with a lot of different connections. This makes it more expensive and time-consuming to install.

Trunk-And-Branch Systems

Home-Run Manifold Systems

Home-run manifold systems use a manifold in which all of the water flows into from a thick ¾ inch diameter pipe. Smaller pipes then run from the manifold connecting into each of your appliances. These systems use the least energy and are generally the most efficient. Hot water will reach your taps quickly, so you won't have to run the water for ages to get it warm.

The home-run manifold is a flexible system and gives you a great deal of control over the flow of water to each application. This allows you to save water, but you will use many pipes to connect everything up.

Home-Run Manifold Systems

Submanifold Systems

Submanifold systems operate with a separate manifold for each room. These can be designed in several different ways and generally use less pipe than other systems. The submanifold systems don’t really offer any benefits over the other two and are less water efficient.

Submanifold Systems

How To A Install Pex Plumbing System: Step By Step Instructions

To plumb your house with PEX, you’ll need to replace your existing pipe. To do this, you’ll need some PEX plumbing tools. There are a few different installation methods, but for DIYers, you'll want to make sure you have two main tools:

  • Crimp rings
  • Cinch clamp (universal size if you can find it)

Then you need to follow these instructions:

  • 1
    Measure Your PEX
    Carefully measure your pipe and make sure you have enough PEX that covers it.
  • 2
    Cut Your PEX Piping
    Carefully cut your PEX to the length you need it. This should be as exact as possible, but the pipe can bend if it needs to. Make sure you cut this straight, so there can be a watertight seal.
  • 3
    Shut Off The Water
    Use the valve to shut off the water supply before doing anything to your pipes.
  • 4
    Remove The Copper Pipe
    Carefully remove the copper pipe from your plumbing. You’ll either need to loosen the nuts and peel it out, or you can cut it down using a hacksaw and connect a copper to PEX adapter into the end. The PEX piping can then be connected into the adapter.
  • 5
    Connect The PEX
    Once you’ve cut the PEX to the appropriate length and removed the old pipe, you can fit your PEX plumbing. Slide a crimp ring over the end of your PEX pipe, and then use the cinch clamp to tighten the connection. Make sure this is completely sealed before you switch the water back on.

PEX plumbing offers a variety of benefits, and you can use it for plumbing your shower, bathroom, and sinks. To replumb small areas, it will typically cost $300-1500. To re-plumb your entire home, it may cost over $5000. This is still significantly cheaper than using other piping, though.


Pex Vs. Copper Pipe: Which Is Better?

PEX and copper both have their advantages and disadvantages. We’ve compared the key factors to help you understand which is best for you:

Pipes Cost

PEX is a lot more affordable than copper. While you will need specialist equipment for PEX, you will save a noticeable amount in the long run.

Ease Of Installation

Copper piping often has complicated connections, and there may be soldering involved. PEX is a lot easier and quicker to install, especially for DIYers.

Corrosion Resistance

Rust is often a common issue with copper pipes which leads to them needing to be replaced. PEX is made entirely from plastic and, therefore, not susceptible to corrosion or rust.

See Related Article: CPVC vs PVC piping


People Also Ask (FAQs)

Is PEX banned in California?

Yes, currently PEX is banned in California as it has not been added to the approved materials list.

What is the difference between Pex-A, B & C?
  • PEX-A
    is formed using the Engel method. This gives the strongest degree of cross-linkage, making it the most durable, and it’s the most flexible making it the easiest to install. It also has the highest kink resistance. This is usually the best option for your home.
  • PEX-B
    is created similarly but is passed through steam at the end. This is less flexible than PEX-A and has much less kink resistance.
  • PEX-C
    is a lot less common and is created using gamma radiation. This is pretty similar to PEX-A and offers a fair amount of flexibility.
How long does PEX plumbing last?

PEX plumbing will typically last over 100 years (barring any damage).

What are the available sizes of PEX tubing and pipes?

PEX piping is usually in a standard size but is available anywhere between ½ inch and 32 inches in diameter. Typically they are available ½, ¾, and 1 inches in diameter.

Does Pex meet the plumbing code?

PEX meets all national codes in the US, but in some local areas, PEX hasn’t been approved (such as California).


Conclusion

PEX is a practical alternative to traditional plumbing that offers a range of benefits. If you’re a DIY plumber, this is the material you want to be using, and hopefully, this article has given you everything you need to know about PEX.

Matt is a freelance writer, English graduate, & keen traveler from the UK. As a specialist plumbing expert, he enjoys writing about everything there has to do with at-home plumbing products & related problems. When he isn’t writing, he’s usually drinking coffee or planning his next adventure. In his spare time, he also runs his own blog all about digital nomad life.

  1. Home
  2. /
  3. Blog
  4. /
  5. Plumbing Schools
  6. /
  7. What Is Pex Plumbing? (Benefits & Disadvantages Explained)
Top