Compression vs Push-Fit connections with plastic/poly tubing

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Vdawg

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TL;DR: Would you prefer a compression connection or a good (i.e. John Guest) push-fit connection specifically for 1/4" or 3/8" plastic/poly tubing (not copper) for long-term reliability against a sudden blow out?

Long Version:
I installed a water filter under my kitchen sink a few years ago. The filter housing uses push-fit connectors to accept the poly tubing that comes in from the water supply and out to the faucet. The faucet's hot water supply line is also a stiff plastic/poly type tubing that was connected (by me) to the hot water shutoff valve using a compression connection. I also have a tee off the post-filter cold water tubing to go to the faucet cold and an instant-hot water tank, the connections of which were made with compression fittings on the plastic tubing to the brass tee. Most of these connections have been in use more than a year with no leaks or other problems.

But recently I also installed a water filter under a cabinet near the fridge to supply both the fridge and a coffee maker, and ended up using push-fit connectors (the filter housing used them as well) on the 1/4" poly line to feed the filter and then tee off the filter's output for each device's supply. I also added a push-fit shutoff valve inline for the coffee-maker filler.

I've always been somewhat nervous about compression fittings on plastic tubing, even with the insert properly in place and using a plastic ferrule. And while I've used SharkBite connectors in a couple of places in my garage on CPVC where they're out in the open and easy to watch, I'm hesitant to use them on a full 1/2" supply pipe inside the house. Although, as mentioned above, I do have a few push-fit connectors on smaller plastic supply lines in the house, so I guess I'm a bit of a hypocrite. :) To be fair, though, I also have water sensors near those connections and under all my sinks and toilet supplies with an auto-shutoff valve on the house's main water line.

Anyway, I'm curious what everyone's opinions are regarding the use of compression fittings on plastic/poly tubing (with insert and plastic ferrule of course) vs. a "good" push-fit connector (i.e. John Guest) for long-term reliability and lowest risk of sudden disconnect. All of these tubes/connections will have some level of motion over time as the valves on the fridge or shutting off the sink faucet are quick actions and do result in some vibration of the tubes and their connections (although in my case, I've tried to "mount/clamp" the tubing to the wall or inside the cabinet wherever possible to minimize movement).

Which of these two types of connections would you feel more confident in their ability, over the long haul, to not abruptly fail and blowout (assuming proper installation)? I not as worried about finding a slow drip leak that I notice days later (I tend to check these areas fairly frequently) as the collateral damage will usually be minimal, but the damage from a sudden blowout is harder to remediate, especially if you're not there to see it for hours after it occurs. :) Just curious about opinions of one vs. the other type of connection, specifically when it comes to use on plastic/poly tubing, not copper.

Thanks!
 

James Henry

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push fit connectors are pretty reliable and so are compression fittings, it's a toss up. I've used both many many times, the only time you may get a leak is if you use copper tubing inside a push fit because the stiff copper bends the teeth inside the push fit. 1/4" pex tubing is stiffer and accepts a compression fitting well. if either system fails they will start to leak first, you will probably never have a fitting blow off unless you did something wrong when you installed it.
 

Water Pro

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TL;DR: Would you prefer a compression connection or a good (i.e. John Guest) push-fit connection specifically for 1/4" or 3/8" plastic/poly tubing (not copper) for long-term reliability against a sudden blow out?

Long Version:
I installed a water filter under my kitchen sink a few years ago. The filter housing uses push-fit connectors to accept the poly tubing that comes in from the water supply and out to the faucet. The faucet's hot water supply line is also a stiff plastic/poly type tubing that was connected (by me) to the hot water shutoff valve using a compression connection. I also have a tee off the post-filter cold water tubing to go to the faucet cold and an instant-hot water tank, the connections of which were made with compression fittings on the plastic tubing to the brass tee. Most of these connections have been in use more than a year with no leaks or other problems.

But recently I also installed a water filter under a cabinet near the fridge to supply both the fridge and a coffee maker, and ended up using push-fit connectors (the filter housing used them as well) on the 1/4" poly line to feed the filter and then tee off the filter's output for each device's supply. I also added a push-fit shutoff valve inline for the coffee-maker filler.

I've always been somewhat nervous about compression fittings on plastic tubing, even with the insert properly in place and using a plastic ferrule. And while I've used SharkBite connectors in a couple of places in my garage on CPVC where they're out in the open and easy to watch, I'm hesitant to use them on a full 1/2" supply pipe inside the house. Although, as mentioned above, I do have a few push-fit connectors on smaller plastic supply lines in the house, so I guess I'm a bit of a hypocrite. :) To be fair, though, I also have water sensors near those connections and under all my sinks and toilet supplies with an auto-shutoff valve on the house's main water line.

Anyway, I'm curious what everyone's opinions are regarding the use of compression fittings on plastic/poly tubing (with insert and plastic ferrule of course) vs. a "good" push-fit connector (i.e. John Guest) for long-term reliability and lowest risk of sudden disconnect. All of these tubes/connections will have some level of motion over time as the valves on the fridge or shutting off the sink faucet are quick actions and do result in some vibration of the tubes and their connections (although in my case, I've tried to "mount/clamp" the tubing to the wall or inside the cabinet wherever possible to minimize movement).

Which of these two types of connections would you feel more confident in their ability, over the long haul, to not abruptly fail and blowout (assuming proper installation)? I not as worried about finding a slow drip leak that I notice days later (I tend to check these areas fairly frequently) as the collateral damage will usually be minimal, but the damage from a sudden blowout is harder to remediate, especially if you're not there to see it for hours after it occurs. :) Just curious about opinions of one vs. the other type of connection, specifically when it comes to use on plastic/poly tubing, not copper.

Thanks!
for 1/4" poly I'd go with a compression fitting. I like the type with the brass ferrule. JG push fits are bulletproof too providing you install the retainer clip. it's all preferences
 

Water Pro

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No offence but you should never use a brass ferrule with plastic tubing because it has been proven to eventually cut through the tubing and cause a leak.
thanks. good to know. I always liked them because you don't have to orient the ferrule. guess I know better now
 

Jeff H Young

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No offence but you should never use a brass ferrule with plastic tubing because it has been proven to eventually cut through the tubing and cause a leak.
James Henry , Agree the plastic ferrule safer. would you extend the warning to pex lav stubs and CPVC stubs as well? Never seen a plastic ferrule on a lav stub out? I encounter very often a standard 5/8 od angle stop compression . my community is built between 2000 and 2010 of a few thousand homes and about 3/4 of them are this way .
to the OP, Ive used a fair amount of push fit under kitchen sinks RO systems and such plus encounter them regularly in service and seem pretty reliable.
 

Jeff H Young

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I seen a ton of cpvc with standard compression stops, but not crazy about it. Id rather see a shark bite , than compression on cpvc
 

Vdawg

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My home was built new in 2013 with some compression stop valves with brass ferrules on CPVC stub-outs for the toilet supplies and a few of the sink faucet supplies (others were CPVC glue-on type). I replaced most of the sink faucet stops with CPVC glue-on valves since the originals had the "crimped-on" supply hose and most of theme were starting to rust around the crimp, so I couldn't just replace the hoses. I used CPVC glue-on valves with 3/8" port (no integral supply hose) so I could use separate hoses which can now be replaced later without removing the valves. I intend to replace the toilet supply valves with the same when I get around to it, even though those didn't use the valves with integrated/crimped hoses. I don't like the idea of a brass ferrule compression fitting on CPVC after reading about how brittle CPVC gets when it ages, and will trust glue-on more for the long haul. At least all the supply hoses they used where the stainless steel braided hoses, even with the integral valves.
 

Reach4

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At least all the supply hoses they used where the stainless steel braided hoses, even with the integral valves.
You understand that those are just rubber tubes with braiding covering the tubes?
 

Vdawg

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Sure -- But I still prefer them over the flexible vinyl supply lines. :)
 

Reach4

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Sure -- But I still prefer them over the flexible vinyl supply lines.
Me too, but I am not actually sure which are better. Better yet would be corrugated metal (not common) or chrome-plated copper tubes. Those copper lines are most reliable and nice-looking. I was mystified by how those semi-rigid tubes could be fit in. I looked around for info, and wrote this: https://terrylove.com/forums/index.php?resources/non-flex-copper-supply-riser.23/
Some day I may actually try it.
 

Jeff H Young

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The glue on stops I dont like because you have to cut back the stubout to change if needed next time.
2013 and they were still running cpvc in Florida! Im wondering if its still going in new houses down there? we dont see much new going in of cpvc. A bunch of our house in our area are the one piece plastic garbage with itregal line they push on stub out so i had to cut it off. the other thing I dont like is waiting for glue to dry, So this is one of the few times ill use shark bites. if it were much older say 25 years old I might be concerned with the glue bonding to such old pipe , but 7 years old Id feel confident .
Good luck its good to see serious homeowners doing the small things to make big differances
 

Vdawg

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The glue on stops I dont like because you have to cut back the stubout to change if needed next time.
The part you glue on is really just a metal female adapter that remains behind a CPVC glued-on "flange" (for lack of a better term). You can unscrew the valve from this female adapter and replace it if necessary without cutting the old adapter off the pipe (assuming the female thread isn't damaged). I actually just did this for all of the bathroom faucet shutoffs recently to get rid of the ones with the integrated supply line (which were rusting anyway) and put on new quarter-turn ball valves (see photo). The originals were the same type of glue-on valve (except multi-turn), so I kept the female threaded part on the original stub-out and just replaced the rubber gasket and screwed in the new valve body. Worked like a charm!

20201222_120945.jpg
 
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