Plumbing Question: Rigid PVC vs Flex PVC

TKpool7683

Bronze Supporter
Jul 18, 2019
29
Cleveland, OH
I am trying to open a can of worms here because I just can't understand this. If rigid PVC is so superior to flexible PVC (when both are schedule 40) why do half of the builders in my area use flex PVC? They're not fly by night builders either, these are reputable builders that have been doing it a long time. In my area the soil is all clay. Termites/insects aren't problem, but you never know what pests or an infestation might show up.

I get that rigid PVC is the superior product for it's durability and longevity. It seems this is the only one someone will actually recommend (people don't recommend flex apparently from what I can find). I can also see how having to do so many connections (if not properly or even improperly) could lend to potential leaks.

I get all the negative things I've seen about flexible PVC: potential insect/termite damage, potential crushing from compaction/backfill/cement/soil weight, etc., and how the ridges on the inside of the pipe can affect flow, and sharp rocks/objects can damage it. I also get how using as much continuous pipe as possible eliminates potential leak points and while you never want the ground to move, flex PVC is probably better than rigid if it does.

Can some of the pros on this site help answer this question for me once and for all? This is the last hold up for me to get started on my pool build here in 2021!
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
3,198
Morris Cnty NJ
I use flex at times only when I have to. I heat bend if I can, but ridgid is superior amd the finish product is too. Most installs w flex are around spas amd main drain feeds to aid in curves. Ridgid is more stable if ground moves actually the pressure is spread out where flex will do just that, but in a small spot. I'm OCD with plumbing I hate to see flex on the pad amd being used for curves instead of quality pipe fitting work. Ridgid just takes more abuse on a jobsite and 20ft lengths leave few fittings.
Older pools are plumbed with poly sprinkler pipe amd many are still working as is today. It's a regional and preference issue as well as time. PBs that plumb their own pools may use flex but i haven't seen am actual plumber do so yet. Mayne repair work but not am actual new install
 

TKpool7683

Bronze Supporter
Jul 18, 2019
29
Cleveland, OH
Thank you @jimmythegreek I really appreciate the insight. I completely get being OCD with the plumbing. I'd much rather spend more time/money to make sure it's done properly than save a few bucks, even if just a small difference in the superiority of rigid vs flex. I want to know the pool/plumbing will last as long as possible.

My previous pool at my old home used that poly sprinkler pipe you mentioned, of course it was built around 1980. All the PBs I've talked to do their own plumbing, don't subcontract out to plumbers, so your comment on that sounds spot on (1/2 do flex, 1/2 do rigid).

@jimmythegreek follow up question: Would you be able to provide any guess/estimate as to longevity of rigid vs flex? (ie. expect rigid to last 50 years, flex to last 40 years) I of course know you can never predict cracks/leaks/problems/etc.
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
3,198
Morris Cnty NJ
I really cant speculate I haven't been around that long. I have dug up PVC from the 80s amd it was in good shape still. I haven't dug much flex its not popular around here. Some that was 15 to 20yrs old was in good shape as well. I just dont have the confidence in it like ridgid. I'm a belt amd suspenders guy, I charge a premium amd I deliver like it's my own home pool
 

TKpool7683

Bronze Supporter
Jul 18, 2019
29
Cleveland, OH
I really cant speculate I haven't been around that long. I have dug up PVC from the 80s amd it was in good shape still. I haven't dug much flex its not popular around here. Some that was 15 to 20yrs old was in good shape as well. I just dont have the confidence in it like ridgid. I'm a belt amd suspenders guy, I charge a premium amd I deliver like it's my own home pool
I completely understand, thanks for the insight!
 

sktn77a

Gold Supporter
May 16, 2010
1,968
Chapel Hill, NC
If rigid PVC is so superior to flexible PVC (when both are schedule 40) why do half of the builders in my area use flex PVC? They're not fly by night builders either, these are reputable builders that have been doing it a long time. In my area the soil is all clay.

I'm not a pool builder but I do have a pool. I also see all kinds of trade activities where reputable(?) companies take the path of least resistance (especially if they are under pressure to meet a budget or deadline). I don't know the answer to your question but my in-laws have a pool built in 1964 with rigid Sch40 PVC pipe and they've never had a leak. I have a 25 year old pool with rigid Sch40 PVC pipe that has never had an issue. Now that's just an "n of 2" but I'd probably want to stick with rigid pipe
 
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TKpool7683

Bronze Supporter
Jul 18, 2019
29
Cleveland, OH
I'm not a pool builder but I do have a pool. I also see all kinds of trade activities where reputable(?) companies take the path of least resistance (especially if they are under pressure to meet a budget or deadline). I don't know the answer to your question but my in-laws have a pool built in 1964 with rigid Sch40 PVC pipe and they've never had a leak. I have a 25 year old pool with rigid Sch40 PVC pipe that has never had an issue. Now that's just an "n of 2" but I'd probably want to stick with rigid pipe
Thanks Keith, definitely makes sense to stick with rigid!