Thread: PVC / CPVC Supply Plumbing

I looked at a home yesterday (actually looking for something to purchase) and all of the supply plumbing was PVC / CPVC. This home is in a semi rural area on a well, and this is about the only time we see this material used. Typically it is limited to something that has been added (usually by a non licensed individual), but in this case, ALL of the supply plumbing originally installed was PVC / CPVC (built in 1991). Overall, it appeared to have been well installed. Most of the surrounding municipalities in this area do not allow the use of PVC / CPVC as supply plumbing today. This is a well built , 2200 sq. ft. ranch style home with a completly unfinished basement. Master bath, jack & jill bath between two bedrooms, kitchen, and laundry sink. Just checking to see if anyone has any MAJOR concerns about such an installation. I guess worst case scenario, 95% of the plumbing is accessesible, but my plans would be to finish the basement at some point in time (thereby covering most of the plumbing with a finished ceiling). Any guess what it would cost a plumber to replace with PEX? Opinions either way are greatly appreciated.

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PVC is not approved for supply. CPVC is. You cannot mix the two materials.

CPVC is fine (if installed properly) there is no need to re-plumb the house just because of CPVC.

Around here the CPVC and PEX ratio for new builds is 80/20 (no copper at all), and on whole house re-plumbs it's about 50/50.

Where exactly is the PVC in the plumbing system?

PVC is rated for supply (water service line), up to the house, but not in it (or in the envelope). Distribution pipe has to be a material rated for that purpose.

PVC is allowed if it is used from the water meter up to the foundation. PVC is not allowed as a water supply under the foundation.

I think that some of the reasons it is not approved by NSF 61 and IRC Table P2904.5 are perhaps the questionable effects that the primers and cements have on potable water, and the appearance sometimes of long longitudinal cracks that can migrate through the piping joints and even through the entire length of piping. It does not seem to be a matter of pressure, as Schedule 40 PVC has a maximum rating of 289 psi. I have never seen a house with over 110 psi. The max allowed is 80 psi.

Maybe someone else on here can elucidate.

Here is a good link to find the suitability of piping for any use:
NSF Certified Products - Public Water Supply System Components

Originally Posted by Bruce Ramsey

PVC is not approved for supply. CPVC is. You cannot mix the two materials.

I concur with Bruce, CPVC is approved for use inside the home and pvc is not. They should not be and usually cannot be mixed because of differing sizes of pipe and different adhesives required.

Expert Mobile & Manufactured Home Inspections O.C. & San Diego Co.

I mentioned PVC as it comes in as PVC, up the foundation wall, across the basement ceiling and back down to the expansion tank & softener. I believe from the softener forward it is all CPVC...

We just don't see it used by licensed plumbers around here. So usually when we do see it, it has been done by Uncle Bob and subsequently, not done right.

I believe that PVC is more susceptible to cracking and breaking that CPVC is (PVC may be more 'brittle' than CPVC?).

I used CPVC back when it was popular and liked it. The glue is a kind of solvent cement that welds the fittings to the pipe. Fittings can break loose if they are subject to twisting, like at a hose bib, for example. Otherwise it is quite durable and has lasted more than 20 years so far.

Change to PEX? I would consider doing that before enclosing the basement ceiling, simply because it would eliminate the doubt. If CPVC was the endall plumbing product, we would still be installing it, which we ain't.

Originally Posted by John Kogel

I used CPVC back when it was popular and liked it. The glue is a kind of solvent cement that welds the fittings to the pipe. Fittings can break loose if they are subject to twisting, like at a hose bib, for example.

John,

If PVC and CPVC are *properly* cleaned, primed, and glued together, you are not going to get that joint apart.

As you stated, the glue is a solvent and welds the plastic of the fitting and the pipe together. However, like a weld in metal, if the weld is not made correctly, then you really have not "welded" the pieces together.

I recently removed out Jacuzzi tub and replaced it with a shower, the tub drain was glued into the top of the trap, I had to cut that PVC off and removed the pipe from within the flared part of the top of the trap - I figured that I was have quite a challenge doing this.

I first saw cut 8 grooves around the pipe which was in the flared part of the top of the trap, this was to give room for the pieces to be dug out easier. I tapped my 1/4" chisel into the defined line between the two glued surfaces and ... the glue joint had either not been cleaned, not been primed, or not been glued properly as that first piece separated at the glue line, 6 of the 8 pieces between the saw cuts come right out like that; 1 piece took some digging to get it out, but was not too bad; the last piece - if they had glued that entire joint like the last piece was glued, I would have had to have dug out the trap and replaced it - that one piece was actually glued in properly.

After chiseling and cutting it out, I had to smooth off the inside to make it like new so I could glue the new fitting in place. I cleaned it, primed it, and glued it, and it is not going to be coming out.

If done properly, yes, the glue does what it is supposed to do - the glue is a solvent and it *does* weld the plastic to the plastic.

Change to PEX? I would consider doing that before enclosing the basement ceiling, simply because it would eliminate the doubt. If CPVC was the endall plumbing product, we would still be installing it, which we ain't.

"If CPVC was the endall plumbing product, we would still be installing it, which we ain't."

Who ain't?

It is being installed in a lot of places by a lot of contractors.

Replace CPVC with PEX? Not a chance, the PEX still relies on crimp rings at each connection and those crimp rings are the weak points. There are places which have already had PEX failures - because of the crimp rings.

PEX is more flexible and thus less susceptible to breakage, however, if PEX is installed properly ... flexibility is not required. So it gets down to this: yes, PEX is easier to just fish in and pull across floor joists and trusses, however, that is not supposed to be done as the PEX could become damaged from nails, truss plates, etc.

EVERY PLUMBING PIPING method has its advantages AND DRAWBACKS - there is no "endall plumbing product" or for any other product either.

It always comes down to the same thing: the installation. If it is not installed properly, it will not serve its purpose as intended, it will fail prematurely.

Jerry, builder's supply stores stopped stocking CPVC here in the 90's. I'm not sure why but I assume it was from too many failures from like you say, bad installations from improper gluing.

If PEX crimp rings are installed improperly, they will leak, usually right away as soon as pressure is applied. I'm not going to say one is better than any other. I'm not a plumber.
I would replace old plastic whatever pipe if there is a chance it is worn or brittle.

The flexibilty of PEX allows for bends instead of junctions. Eliminating a few junctions inside the walls is a good thing.

JP: Nobody in Texas installs CPVC in residential buildings here except skanks in the sticks.

Originally Posted by John Kogel

If PEX crimp rings are installed improperly, they will leak, usually right away as soon as pressure is applied.

Nope, the problems are from PEX crimp failures which occur after the PEX has been installed, tested, passed inspection, and covered over.

Originally Posted by Aaron Miller

JP: Nobody in Texas installs CPVC in residential buildings here except skanks in the sticks.

They use copper, then?

Originally Posted by Jerry Peck

They use copper, then?

Mostly PEX, copper for the better builders. No CPVC except in unincorporated areas with no oversight or for water heater TPR and pan drains.

Then there's the plastic pail and the slop bucket, but that would be further out of town, eh?

Originally Posted by Dom D'Agostino

Around here the CPVC and PEX ratio for new builds is 80/20 (no copper at all), and on whole house re-plumbs it's about 50/50.

As I said previously....

Originally Posted by Jerry Peck

Nope, the problems are from PEX crimp failures which occur after the PEX has been installed, tested, passed inspection, and covered over.

We used to have similar problems with polybutylene pipe, the crimp ring failure. If you're special little crimp tool isn't calibrated properly the ring is to tight or to loose and both fail. Another problem in pb was the quality of the weld in the copper unions. They'd fail and spray a pinhole sized stream of hot water at the subfloor and cause considerable damage.
It never was the pipe just the fittings that were bad. They got sued and had to do thousands of repipes.
Expert Mobile & Manufactured Home Inspections O.C. & San Diego Co.