CPVC or PEX for re-pipe

"It needs to be understood that everything needs maintenance and repair/replacement. This is no different for plumbing systems in houses."

There is a bit of a difference. You will usually see siding start to crack and peel and even if it just broke off you can see and repair if before any major damage. But when a plumbing pipe burst and you are not home, thousands of dollars of damage can occur. Maybe the only thing that is equivalent is a roof blowing off in a hurricane.

bilskro said:

I know exactly what you are talking about as I have been there. But cannot use copper here and CPVC has been around a long time. I am just afraid to be the pex guinea pig. Who knows how it will hold up after 20 years in Jacksonville harsh water. We might be saying Darn should have gone with CPVC. But right now I am leaning towards pex.

Click to expand...

You are far from being a guinea pig.

https://failures.wikispaces.com/PEX+Plumbing+Failures

PEX Failures

With the sudden increase in the use of PEX in recent years, failures in PEX plumbing systems have been observed. Failures can be linked to two areas; the pipe and the fitting. The pipe can fail when exposed to chlorine within the water, or over exposure to sunlight before installation. In addition, PEX pipe has also been found to be permeable when exposed to some solutions, including oxygen and some petroleum products, and can leach toxic chemicals from the pipe material. As far as the fitting, the leading cause of failure in a brass fitting used with PEX is caused by dezincification. This causes the fitting to corrode and eventually create leaks.


Until I no longer was, I was a hardcore all copper builder. Even when the other national names had switched to pvc & cpvc, I insisted on copper - it was a hallmark of the brand, just like the famous architect I used.


The link below is Google Earth of our 1500 front door project in Oxford. The first 150 or so were done with copper before the switch to PEX in about 2001-2003. So that's a good long major project reference with a 10 year build cycle.

Took the plumber forever to get me to change my mind.

I have ZERO regrets.

Let me know if the Google link doesn't work - I've never tried posting that type before.

If you get it right, you could "drive" through the whole thing via Google - will take you awhile.

https://www.google.com/maps/@42.8334215,-83.29081,2108m/data=!3m1!1e3

I'd always go CPVC, mice chew PEX

Pex has significant freezing advantages, but at the end of the day CPVC works fine and is more proven than PEX.

1) There is nothing easier than gluing together CPVC pipe, not crimping, not expanding... nothing. The cutters are easy to use in tight spaces. A glue dapper is easier than any crimping or expanding tool. Follow the glue rules is easier than following crimping or expanding rules. A cheap pair of tubing cutters is good enough for small jobs, Rigid ratchet cutters are probably the best.

2) The CPVC pipe is the ideal balance of rigid and flexible to run pipe straight like copper or run it messy like PEX. Giving customers the option to run homerun/manifold plumbing is a nightmare. Houses are not designed around using that much additional pipe, it can create a lot of unusual problems, which cost labor money or screw one party or another in the quote. Homeruns and manifolds are not worth the money. Pressure is mostly determined by faucet and supply tubes from the valves, not pipe. Most households don't run enough stuff at once for the homerun system to shine. The limit is most often your faucet, your water service, your filtration system or your tankless hot water system is clogging and the pressure balance faucets are balancing to the lower hot. On a side note. Tankless heaters are almost never worth the money/hassle. They don't save enough for the massive additional maintenance that MIGHT be involved and that is based on water quality, which is beyond the plumbers control. Water softeners don't actually prevent all the minerals from scaling pipe, only some of them. So, it will always be a bit of a risk to go tankless.

3) CPVC is cheap and does not require many tools. It does the job fine, there is no need to look for another option. If you have a proven option that's easy, stop looking for other options.

4) There is no real problem with CPVC getting old and brittle. A standard house generally doesn't outlast it's plumbing all that often anyway (unless you used quest pipe). This is just people whining about things because they are not perfect AND trying to sell PEX. The reality here is that usually it doesn't happen with a decent/sharp snap closed or ratchet style cutter. BUT, if that's a problem just use the old copper cutter or a hacksaw. DERP. It's like nobody thought of that? It's still going to be 5 times easier than running copper.

5) The only REAL problem with CPVC is not following the instructions on the glue label. You don't want to jam much glue into the fitting. but only a thin layer on the inside of the fitting. You can apply as much as you want to the pipe. Then hold for a few seconds and boom your done. The instructions are pretty clear on how to use it. I always use Oatey Orange because it sets a little faster, which is ideal for repairs or installation. For drain the fast setting glue is not worth it, imo.

6) Other limits of CPVC are that you need dry pipe and fittings. You need a fresh glue supply and you need to recognize when glue gets old and gels up and throw it out. It may not be the best pipe in extreme conditions when compared to PEX, but those extreme conditions generally don't exist in 99% of proper plumbing installs. You need a way to carry pipe in straight lengths and not rolls and you need more different types of fittings to run the pipe in the ideal way.

As a plumber I say PEX does not have useful real world advantage over CPVC unless perhaps the pipes are routinely exposed to freezing conditions for some reason, and they never should be. I would prefer to insulate CPVC and seal up the crawl space as the proper solution to freezing pipe issues.

I see no reason to ever use pex for water pipe. I might use it for radiant heat, but I have a big problem with pex.

In multiple homes around here as well an RV. Mice have chewed through the PEX pipe. We've never seen mice chew through CPVC in 40+ years of plumbing. We've never seen CPVC pipe spontaneously fail or develop pipe holes like copper.

The only real complaint is that it gets brittle, but unless it's installed wrong and the glue was junk or the pipe was wet, the glue joint holds up JUST like the ever important drain glue joints all over your house. I think using PVC drains and CVPC water pipe is about as ideal as it currently gets for a plumber. PVC is our friend!

The brittle problem is easy to get around and installation time is low. I suspect CPVC will wind up holding up better than copper since it's far more resistant to acidic water conditions, which was one of the major failing points of copper, the house full of pinhole leaks.

Copper is still the best of the best for anyone with decent water, but if I had low PH water I think a CPVC install would last longer. Pex is prone to mice chewing through it, but other than that it MIGHT last a long time. I think, over the course of a homes entire life, mice could prove to be a long term nightmare for PEX installs. Hopefully the houses are sealed up real good or not in climates with small insects that like to chew soft plastic. I don't want the liability of a PEX, but even without that glued joints are faster and don't require special tools. I don't like coiled pipe one bit. If I wanted to run CPVC sloppy, like pex, I could do that and run it a little faster, but ... why.

If homeowners want to work on their own pipe, CPVC is easier I think. Sharkbites made transitions easy on most any pipe these days. I dunno how long those things will prove to last. I've seen them leak, but people probably also didn't follow the instructions and prepare the pipe.

Just don't jam glue in the fitting, don't use old gelled up glue and don't get the pipe or glue wet and hold the fitting together. I like to twist the fittings when I can to helps ensure the best joint. Like drain PVC, the pipe will sometimes want to push out a little when you first glue it together. Sometimes they will, sometimes they won't. You just hold them in for a few seconds, which technically changes with the temp, and you're fine.

I'm just a plumber, my dad is a plumber, I'm not trying to sell you anything other than the concept of staying with a proven and highly standardized piping system. CPVC is the more proven choice and all the talk about it being brittle is highly exaggerated.

If that were true, to the point some people say, as plumbers we'd see it happen. How is it we've seen more mice chew through PEX than we've seen people just break off CPVC? How come so many people use CPVC? How come it's all part of accepted code? Wouldn't we have massive class action lawsuits like the kind that put quest out of business?

Now.. years ago the CPVC pipe was a different formula. Maybe some of the first batches were not good or consistent and there are some bad installs out there. I think that's where copper wins, it's hard to mess up the copper 'formula'. However, it's easy to mess up the fittings and have a batch that are hard together, while CPVC fittings are never hard to put together or require sanding or reaming to get together.

I've worked on some old CPVC and only ever experienced mild brittleness, which meant we just cut it with copper tubing cutters. We have lots of old retrofitted farm houses around here, so I see a decent amount of old sloppy CPVC. We've never seen it just break and fail unless the cabinet guy or something broke it off and that can even happen with new pipe if you hit it hard. I'm sure PEX can get punctured in the same ways, especially since we know mice can chew through it. It is soft plastic. If pex was self healing and puncture proof, then it would really be something.

By code I still have to insulate PEX, which means nailing the pipe right to the wood kind of sucks compared to setting things up in a way that will make insulating the hot side easier. Saving time on the install and running sloppy pipe then losing time on insulating doesn't make much sense. Fighting rolls of pipe trying to make big bends takes time. Using crimp or expanding fittings takes time. I just don't see the advantage at all unless you run pipe like you TOTALLY don't give a crap, in which case you MIGHT out run me running CPVC at max sloppy level, but I doubt it.

The only thing I have working against me is glue drying time to get the air test, but realistically we don't charge by the minute anyway. A CVPC repair might take 20 minutes and include 30 minutes of drying time while we do nothing, but you'd get charged an hour either way. The PEX repair would cost the same, but WE could leave the job sooner and go to another job.

That's the real advantage of PEX, but it's not something that plays out in the real world as good as it does on paper. I can always just shark bite repair a CPVC leak and roll out if I had to. The reality is that plumbing jobs are diverse and hard to a lot time to because of the huge variety of plumbing in homes from now and dating back 100 years. The minor advantage of PEX for rapid repairs isn't likely to add up to much unless you somehow specialize in PEX water line repairs only.

Maybe in extra cold climates PEX wins out, but really your house should protect your plumbing.

Or in climates that have a cold spell at least once a year?

Their both junk.