Pros & Cons of Different Piping Materials

Most people don’t really want to be thinking about plumbing materials… We just want plumbing to work flawlessly, forever! That’s nice, but reality does intervene sometimes and we then need to understand the practical considerations so we can get closer to our goals of flawless and forever.
 
So, here we go! Each piping material has different strengths and weaknesses. Sometimes the conditions piping will live in, or job site considerations affect which material or materials are best. Here I’ll go over some of the considerations that help to create a long lived, efficient and trouble-free system. I’ll take it one material at a time except where there may be interactions.
To start, we’re looking only at water distribution piping here. Drainage, fuels, or compressed air all have different considerations.
 
Let’s start with Galvanized Steel pipe, Pros:
 

• It’s strong! It’s the strongest of conventional piping materials. It even resists nails, which the other common piping materials don’t.
• It is considered to be a fifty year material, but in good water conditions can last far longer.
• As it is metal, it withstands sunlight, heat and solvents.
• It can be assembled wet.

Cons:

• Steel rusts. When the zinc coating is used up, the steel will rust. This often builds up inside of the pipe, restricting flow and adding rust to the water.
• The galvanizing process may involve the use of lead. Lead is not good for us.
• Steel pipe is the most difficult modern material to install. Its strength and lack of flexibility make it harder to fit into place, particularly in remodel work. Threading also requires special tools.
• Where it’s joined with brass, like at a valve, the brass will force the steel to rust away much faster.

Copper Pipe Pros:

• Copper is far lighter than galvanized steel pipe and is easier to connect, using either soldering or press fittings.
• Soldering does require some experience to do right, but it’s easily learned.
• Copper is unaffected by sunlight, moderate heat and solvents, just like steel.
• Copper seldom builds up enough scale inside to restrict flow.
  

Cons:

• It is subject to erosion corrosion, caused by water travelling too fast and thinning down the pipe.
• Nails go right through copper pipe.
• If water in the pipe freezes, it will likely burst the copper.
• It requires a torch (needs some skill) or press tool, (not cheap).
• Copper has become expensive.

 
PVC/CPVC Pipe Pros:

• PVC/CPVC is lightweight and simple to glue together.
• It is somewhat flexible, and easier to snake around obstructions than the metal pipe materials.
• It essentially does not scale up inside.
• It’s fairly inexpensive.
• Needs no special tools

Cons:

• PVC/CPVC does not like long exposure to sunlight as it becomes brittle.
• Freezing can ruin entire runs of this piping as it tends to split lengthwise.
• As it is softer than metals, it needs more, closer spaced supports.
• There is concern that it leaches plasticizers into the water… un-healthy.
• It cannot take the heat that metal piping can and will deform if it gets too hot,

though CPVC takes heat much better than PVC does.

• Not rodent proof.

PEX Tubing Pros:

• PEX usually comes in coils, so is flexible and requires fewer fittings to get around.
• It’s the easiest material to use for retrofit construction as it flexes so well.
• It is the smoothest piping material, so can handle higher flow rates, (up to ten feet per second) without damage… though the plastic fittings hold up better to this that the brass fittings.
• It can be assembles even with some water in it.
• It is freeze resistant… not freeze proof!  It can expand with ice inside, but returns to its normal shape when the ice melts.
• It’s a good material if you have high water pressure as it will help absorb the shock of water hammer.

Cons:

• PEX does NOT like sunlight. It must not be exposed for any significant time during storage or be installed so it sees the sun.
• Chemicals can leach directly through the material.
• PEX is slightly smaller inside than copper, so depending on flow rate, may have more pressure drop along the length of the pipe.
• It happens very rarely, but rodents can chew through PEX. It needs to be protected when run through rodent living rooms.
• PEX insert fittings substantially reduce the ID of the tube, so increase friction loss. Best to use a PEX system (like Uponor) that expands the tube to go over fittings.
• PEX requires the use of special tools.

As you can see, there are things to keep in mind when deciding on a piping material. So much depends on the situation the pipe will live in and how difficult it will be to install the pipe.
As a rule, it’s always easier to install smaller diameter piping. So, consider low flow fixtures when you remodel. This way you might be able to run really small stuff like 3/8” PEX, or soft copper (or smaller if allowed!).  This becomes very much like running wiring, it’s so small and flexible. Also, it can be put in places that larger pipe wouldn’t fit, like flat raceway or hollowed baseboard.
This was just a quick overview, but hopefully it will help you to think less about and spend less time with plumbing. For fun, here’s a quote from Thomas Drummond, 1797-1840; “Property has its duties as well as its rights.”
 
Yours, Larry

---