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topic 25165

CPVC vs. PVC piping Safety Question


Q. I found this website by a rather non-specific search, so I hope this ends up in the right place. We are considering having a house built, and the builder uses CPVC plumbing. I read the post about the making of CPVC and its greater (than PVC) temperature resistance. Other than that, why is CPVC safe, when PVC wasn't? I'd really appreciate any response.

Jordan Van Dyke
airline - Canton, Ohio


A. Hi Jordan,

Well, I really DON'T know! They are both 'safe' materials and highly acid/alkali resistant with the edge going only to CPVC re temperature.

For a house I'd consider perhaps PVC for the cold water lines (or copper) and CPVC perhaps (but certainly copper) for the hot water ... and most definitely, emphatically ABS for all the drain lines (which, incidentally, has a higher temp. resistance than PVC). How to check? PVC is grey (for Sch.80) otherwise white, CPVC is normally a lighter grey and good ole AcrylonitrileButadieneStyrene is black.

CPVC would cost an arm and a leg, too. I hope that this response is what you want but if you have any further questions, lemme kno !

freeman newton portrait
Freeman Newton
White Rock, British Columbia, Canada

(It is our sad duty to
advise that Freeman passed away
April 21, 2012. R.I.P. old friend).


A. Sorry to pop your bubble, but PVC is safe for plumbing. Another product was banned, polybutylene. It failed structurally after a few years. It was used for hot water. PVC is not adequate for temperatures of most hot water in most houses. When in doubt, go copper.

James Watts
- Navarre, Florida


A. I am no engineer but I just purchased a house where everything is run in PVD. I have about 6 foot of copper coming out of the water heater and that's it. I am not sure when the previous homeowner installed the PVD but I do know that upon having the water turned on I had many joints that leaked like crazy. Copper is the best: a solder joint lasts around 50 to 100 years at the least, a glue joint will get, what, ten.

Nicholas Williams
- Hamilton, Ohio


A. I am a general contractor in Texas, I have experience with all types of pipe and can comment on this subject.
copper is the best if you can afford it.
PVD will last forever with proper glue joints and below 100 degrees max temp. above that it will weaken and fail over time. I use the PVD in underground and interior wall applications for COLD WATER ONLY.
CPVC is less expensive than copper so I am using it on the hot water in homes only. But it will become brittle with time.
If it is exposed to sunlight or excessive heat for a long time it will fail. [example: you can use the burner on the stove and heat PVD and it will bend easily, try it sometime if you want to bend PVD to go around corners, saves on fittings ]

If you want to build your own plumbing system [new house or retrofit). Use copper for hot water and PVC for cold.
Use a copper heat trap on the cold inlet to the water heater so the heat doesn't reach the PVD cold inlet pipe. This system will last forever and cost less than copper only.
** note: with PVD be sure to anchor the pipe every two feet to prevent sagging and movement that will cause damage to plastic..
Good luck.

Barney Butler
- Waller, Texas

November 19, 2009

A. CPVC is good for hot water and cold. furthermore, it can bear 93 deg C and high pressure of more than 15 bar. and regarding the sunlight. CPVC can resist that because of the way how it was made (chlorinated).
At my work site we are replacing the copper pipes with the CPVC for hot water and cold water which is exposed to the sun.

Zuhair Hasan, maintenance - supervisor
- Manama, Bahrain

July 1, 2010

A. Because I hold a master plumber license from the State Board of Plumbing Examiners, I feel competent to post an answer to this question. Is PVC safe? As for water consumption from a PVC pipe, yes, it is safe. Now, is it safe to plumb the inside of your home with PVC? The answer according to the International (section 605.4) and Uniform (section 604.1) Plumbing Codes is NO!

One reason for this is thermal expansion. PVC is not rated for hot water. Even though a contractor installs PVC on the cold water supply side of the system, PVC still comes in contact with hot water.

Let me explain. When water is heated, it expands. If you were to touch both the cold side inlet and hot side outlet at a water heater, you probably would not know which one was the cold side or which one was the hot side. They are both warm. That's because the heated (expanded) water must travel somewhere when the hot side cannot accommodate the room. The cold side system will allow water to travel back into it's point of origin. Point of origin can be at a water meter, well pump, etc. So, in the long run of this answer, PVC pipe is not rated for hot water and using PVC can lead to leaks causing structural damage to the home.

I have also heard the question "Won't a thermal expansion tank eliminate this problem?" No, the tank can only hold so much pressure, heat will still continue to travel through the lines.

As for a cost factor, yes, copper is expensive. According to code, a home can be plumbed with CPVC on the hot and cold sides of the system.

I hope this helps. Have a great day!

Susan Rouse
- Universal City, Texas

August 13, 2010

Q. Aside from the dangers of PVC leaking over time when used for Hot water, are there any dangers of the PVC leaching chemicals when used for Hot water?

Keith Bien
- Wildwood, Georgia

July 7, 2011

Q. I have a question about running a PVC water supply line. I am going to need to install a water supply line to our new house in a few days, and in our area of the country there is a lot of rock in the soil; so much so that a rock saw is going to be needed to dig the trench for the water line. My question is, at two feet down, is the soil stable enough not to break the glue connections of the PVC pipe from movement? Should I run the 2" water line inside of perhaps a 4" pipe so that the larger pipe takes the strain of any soil movement? (I actually thought that the rock would make for much less soil movement, but the water main installer for the water co-op mentioned it.)

Any thoughts would be appreciated.

Edwin in Texas

Edwin Stephens
- Fort Worth, Texas

December 29, 2011

Q. Red Hot solvent versus IPS 711 for a industrial application? Water intake drinking water for the city Of Stockton, CA. The supply piping is copper the vents are PVC on the outside of the wall studs.
That blue color is not very pleasing to the eye on a white and grey background.

Bob Carlon
- Santa Maria, California

January, 2012

A. Hi, Bob.

Sorry, but I'm not understanding your question. Red Hot is a dry chemical consisting of sodium hydroxide and aluminum that gets hot when wet, to better clear clogged drain lines. IPS, as far as I could quickly learn, is apparently a PVC glue. So, does "blue ... on a white and grey background" imply that the glue is blue and unattractive on gray and white PVC plumbing? What is the question?


Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

January 16, 2012

A. After experiencing 2 major CPVC plumbing failures in the last 2 years - - in a house that was only built in 1998, I'm very skeptical about even CPVC from a durability point of view. The pipes from the removal were extremely brittle! And the installation only had 4 feet of copper from the hot water tank before it transitioned. What do we really know about PEX? Are we going to see major failures from this stuff in 10-15 years? I also heard it is completely compromised if rodents decide to chew on it. Not that any home invites rodents, but it happens. Pay now or pay later?

Jon Day
- Tacoma, Washington, USA

January 16, 2012

A. Thanks, Jon. I lack the experience of some the contractors and plumbers who have posted here. But I have seen a hundred different plastics used in a thousand applications, and all seem to suffer "aging" to some degree because the plasticizers eventually dissipate. All of my cars, which are far less than 20 years old, have had all sorts of plastic stuff breaking under the hood. The plastic insulation on every old wire I have ever seen is hardened if not otherwise deteriorating. If we have less than twenty years experience with a given plastic in a given application, I hesitate to project that it will last 50 years, or forever :-)


Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

February 15, 2012

Q. Which plastic is better for Sodium Hypochlorite Injection system.? Any comments will be appreciated. Thanks.

Suman Dey
- Malaysia

April 16, 2012

A. The difference between CPVC and PVC is the temperature rating. PVC is only rated for up to 140 degrees F. CPVC is rated for up to 180 degrees Fahrenheit. All plastic pipe will degrade in sunlight unless it has Ultra Violet Light inhibitors. PVC Electrical Conduit is gray because of the UV inhibitors. PVC and CPVC should not be installed where it is exposed in direct sunlight. Insulation would be acceptable for UV protection. Make sure the Insulation jacket is UV protected.

Ron George, CPD, Plumbing designer
- Monroe, Michigan, USA

September 12, 2012

I am a plumbing engineer, licensed Master Plumber, Lecturer and Teacher of Plumbing. I can tell you that PEX piping has been used in Europe for over 50 years with few failures of the piping. There have been failures with the fittings, that have been affected by the amount of the chlorine in the water or with the brass fittings with dezincification. PVC and CPVC also have been affected by failures as well as copper. In many areas of the country the nature of the water is such that it eats holes in the copper piping. In some cities in Minnesota it is not allowed because the water is slightly acidic. There is no perfect system. Every system must be designed for the local area and the conditions that will affect it. CPVC is a good piping when not near the water heater, which will ultimately cause a failure, especially tankless water heaters that can have a higher temperature than electric. We have investigated cases of failure as the CPVC expanded over time till a 1/2 inch pipe was 3" in diameter. A mixture of different systems can increase your lifetime of the water piping system. Using Copper piping as a heat sink away from the water heater for 6 to 10 feet on the hot leg and 2 to 4 feet on the cold leg will decrease the possibility of failure.

Ray VinZant
- St Paul, Minnesota, USA

September 12, 2012

thumbs up signThanks Vince.

I have always felt that if one material were manifestly and universally better than another, the other would disappear from use.


Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

November 12, 2013

Q. I would like to run a CPVC line up and over my ceiling to my kitchen sink. Can I do this safely?

Tom Jenkins
- Ypsilanti, Michigan

February 17, 2016

A. I plumbed my home 30 YEARS ago with straight PVC, hot and cold water and have had no leaks at all. I had a plumber come over to hook up a new water heater and he refused because of it. He said "You're going to have leaks everywhere!" It hasn't leaked in 30 years and he couldn't believe it. So, I don't believe all the CPVC hype.

Robert Hand
- Jacksonville Beach, Florida. USA

April 11, 2016

! PVC is a lead-dirty plastic. Lead leaches from PVC pipe and should not be used for incoming water. The medical community in the US now acknowledges that there is NO safe level of lead. Unfortunately it will take time for the trickle down of information and implementation. If you are building now, avoid PVCs and be ahead of the curve.

Leslie Davidson
- The Villages, Florida USA

April 2016

thumbs up signThanks Leslie! My understanding from some quick googling is that European PVC potable water piping has been lead-free since 2005, and the EU target was no lead stabilizers in any PVC by 2015 (I'm not sure whether they made it on schedule). Only tin stabilizers have been used in American-made PVC pipe for a long time now, so there should be no worries with Made-In-USA pipe.

Pipe from China still largely uses lead stabilizers, and if they claimed that some particular piece of pipe didn't, I probably wouldn't believe it without piece by piece testing, so it it vitally important to only use pipe with unambiguous Made-In-USA labels.

Lead Poisoning

That there appears to be "no safe level" is important to recognize, but there is no such thing as zero of course, so we have to recognize the law of diminishing returns: if we are getting x picograms of lead from source C, and 0.00x picograms from source P, we need to focus all of our immediate efforts on C.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

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