flex tube & vacuum force

Johnny B

LifeTime Supporter
Mar 19, 2009
Charlotte, NC
Photo is from another thread, can’t find that threadm but don’t need to for this question.
The main cause of the failure/collapse of this flex tube was shoddy construction in combination with some chemical damage but mainly vacuum force.
Question : when you say vacuum force, you mean mostly from the pressure difference/change when the pump goes from On to Off or vice versa, right?
Not vacuum force when I turn a jandy valve while the pump is running? Reason I ask: my jandy valve is old (but not leaking so fine) so I can rarely make a “slow gentle gradual turn” (the single jandy I am concerned about controls both the skimmer & the drain). I am wondering if my less-than-gentle turning of that jandy is rough/undesirable insofar as possibly creating another collapse in the flex tube that remains (we did change out the collapsed one obviously).
I can get a new neverlube jandy (that will allow gentle turning) but I’d rather not if I don’t need it. Flex pipe collapse “from vacuum force” is more an issue of the “pump going On to Off or vice versa” than an issue of “too quickly turning the jandy while the pump is running”?




TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
Pipes on the suction side of the plumbing does run at lower pressure than atmospheric pressure, thus there is what is commonly called a partial vacuum on that pipe. Since there is less pressure inside the pipe, atmospheric pressure pushes from outside, and can in some instances crush the pipe, especially if it is clogged at the pool end. More or less every time, there is something else wrong as well. Good quality pipe doesn't crush all that easily.

The issue with turning the valve has to do with pressure spikes, not vacuum force. Pressure spikes will cause the pipe to shift/flex. Over time that can encourage an "almost kink" in the pipe to start to crimp and eventually collapse. It also puts pressure on all of the joints, which may fail over time if they weren't perfect to begin with. Pressure spikes are also rough on the above ground plumbing as well.


That is a perfect example of why I will not allow flex pipe in any job I am on :evil: :evil:

I'm sorry to see that. There is no code that I am aware of that says you cannot use flex pipe, but I still feel it is wrong to use. It is just an easy way to plumb; not the best way to plumb. I always use rigid pipe, no matter how difficult or how much more time it may cost me to make it line up. Do it right or don't do it, in my opinion!

Again, I am sorry to see that. I would make the repairs (and any other pipe you can get to) in rigid, Schedule 40 PVC. No more problems when it is done correctly!


LifeTime Supporter
Jun 4, 2010
Columbus, Ohio
Ugh. This is really fantastic. Why couldn't I have found this site in December and not May?

My concrete guy is coming to my house in 2 hours to plan out the deck.....so obviously we are close to done and all the pipes are backfilled.......but my PB used all 1.5" flex pipe. Sweet.....now I want to just dig it all up and start over as that seems cheaper than tearing out the concrete years from now.

My journey hasn't been pleasant for the most part as the PB has complained over and over about how he underbid the job and he's taken over 2 months now to do it because he's had some legitimate setbacks and had to still open pools for his other customers. All in all though he's done what I thought was a good job.......I was hoping not to have construction regrets.

Thanks for adding to my stress. :) I'm really just kidding, I'm glad I found this site, just wish I'd done it earlier.


TFP Expert
LifeTime Supporter
Mar 29, 2007
Coastalish 'down easter'
Welcome to TFP!!

While I completely agree with Bruce's thoughts on the flex - I've been using it for 10 years now and the only troubles I can identify are:

1) Termites will chew right through the stuff :evil: (however, if you have termites eating your pool plumbing - the house is next to go)

2) If the back yard is 'mud soup' - the weight of the excavator will crush the pipes allowing for total failure ~5 years down the road as the pool is backfilled.

I hear your pain and understand your apprehension! The flex will only collapse if it's damaged BEFORE the suction vacuum is created. Take a look at the makings of that piece - there's a plastic 'wire' that provides the integrity to the pipe, if it's compromised - the pipe will eventually fail :(

I'm more than happy to discuss this further, but flex isn't as bad as some might suggest :)


LifeTime Supporter
Jun 4, 2010
Columbus, Ohio
Thanks Waste. The concrete guy came out tonight and he wasn't pleased. Apparently the PB put the pool in too low, so I have plenty of things to worry about over the long haul. The good news is the concrete guy did a huge job for me last year on my driveway and while I don't say this about contractors very often....he did an absolutely fabulous job and he is my "concrete guy" from now on!! He says we can make it work, but he's worried about the excavation time involved to take out some dirt. Another thread....sorry, but I'm obviously a little stressed right now.

Anyway, I'll do what I can to reduce my future issues with my plumbing. I will insist the concrete guys stays off the area where the pipes are buried (I'll even offer to help hand did that area if he prefers). I'll also get a bug company out to work on treating my property for termites. I live in a woods and its a relatively new build, so we need to do it anyway.

Thanks for your advice.

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