Swimming Pool Plumbing: Rigid PVC vs. Flexible PVC, Which is Better?
Visit any online pool and spa forum and you'll find that a leak is one of the most frustrating experiences a pool owner can have. Finding, fixing, and not to mention paying for a leak will make anyone want to pull their hair out!
Needless to say, a pool builder needs to use the best installation methods and building materials available to prevent leaks along with all the nasty consequences that follow.
Today I want to turn our attention to the most fundamental component of a pool's plumbing: Polyvinyl Chloride tubing, or PVC pipe.
There are two primary types of PVC pipe used in residential inground pool construction today:
- Rigid PVC pipe
- Flexible PVC pipe
Let's compare these subterranean tubes to determine which you would rather have under your pool patio.
Is rigid or flexible PVC pipe better for inground pool plumbing?
You should use only rigid PVC pipe for the plumbing in your inground swimming pool. Even though it's more difficult to install, it's much stronger than flexible PVC pipe, which isn't rated for underground use at all. Flexible PVC is easy to crush or puncture, and bugs like termites can chew through it.
What's the difference between rigid PVC and flexible PVS for pool plumbing?
What rigid PVC and flexible PVC have in common:
- Rigid PVC and flexible PVC pipes both have essentially the same chemical make-up.
- Both are cut and glued using the same tools and solvents.
- They are joined together using the same PVC fittings.
What makes rigid PVC and flexible PVC different:
- Rigid pipe, just as its name implies, doesn't bend on its own. This means whenever a turn in the pipe is needed, the installer either has to cut the pipe and install a fitting or heat bend the pipe to get around the turn. Both take time and varying degrees of skill.
- Flexible PVC is made with plasticizers that make it softer and highly flexible. When a turn in flexible PVC is needed the installer simply forms the pipe around the bend and keeps on rolling. This method of installation is much quicker and easier than using rigid PVC pipe.
So far, we can basically see that we have a choice between a pipe that is stronger and more difficult to install verses one that is weaker and easier to install.
All things being equal, I'm going with the one that's easier to install! But alas, things are never quite that simple, are they?
Here's the deal:
Flexible PVC pipe is much easier to install, but should never be used on an inground swimming pool...period!
The short answer:
Let's talk about that.
First of all, several years ago I attended a seminar on inground pool plumbing. The instructor passed a small section of pipe around the room. When it finally came around to me, I was astonished! It was a piece of 2" flexible PVC pipe with dozens of tiny holes in it. My first thought was "What the heck?"
Then the instructor said one word: "Termites!"
Flexible PVC pipe is simply not suitable for underground use, but don't take my word for it.
Kuriyama of America, a large distributor of flexible PVC states:
"....Spa Hoses (flexible PVC pipe) can be damaged by rodents or insects, including termites. Spa Hose should not be used underground in areas infested by termites. Our warranty does not cover damages caused by them...This product warning shall be given to every purchaser of Spa Hose. (Rev. 7/98)"
PlumbingSupply.com has this at the bottom of their flexible PVC page:
"Note: Spa Hoses can be damaged by rodents or insects, including termites."
Do I even need to ask if you have termites? Does it really matter? Why would you take the chance?
The more appropriate question is: Why would a pool builder take the chance?
Second, flexible PVC pipe is much easier to puncture or crush than rigid PVC pipe. It's simply not as strong, and considering all the pressures exerted on underground pipe, strength is a good thing!
I have seen "flex pipe" crushed and punctured both during construction and while working in a yard with existing pipe in the ground.
Anyone digging in a back yard needs to use caution, but personally, I would feel much more comfortable digging in a backyard that I know has rigid pipe versus flex pipe.
So why is flexible PVC used on inground pools?
Although the swimming pool contractors that use flexible PVC on inground pools are in the minority, they are out there.
I believe and hope it's because they don't know any better. There's no doubt that it saves time, and we all know that time is money.
The real question is: "Will you have it in your back yard?"
Needless to say, I wouldn't, and neither will any of my customers! The last thing we need is to feed the termite population and waste our time finding and fixing leaks!
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Editor's note: This blog article was updated on January 30, 2019.