What CPVC and PEX are
CPVC is chlorinated polyvinyl chloride: rigid, cream or tan — the FlowGuard Gold product has a distinctive yellow-tan cast — and joined with solvent cement, the way PVC drain pipe is. In North Texas it is the characteristic 1990s supply material, sitting between the copper and polybutylene era and the PEX era that followed.
PEX is crosslinked polyethylene: flexible, supplied in coils, joined mechanically rather than chemically. It displaced CPVC and most remaining copper through the 2000s and is effectively universal in new construction.
The rough DFW era assignment runs galvanised steel before 1960, copper through the 1960s and 1970s, polybutylene in a subset of houses from roughly 1978 to 1995, CPVC through the 1990s, and PEX from the 2000s onward. Treat that as a screening heuristic and nothing more — the transition years are trade generalisations, and nobody has published the year any specific North Texas city changed over.
A second change matters more than the material change and almost nobody writes about it. Newer construction commonly runs supply lines overhead through the attic rather than under the slab. That is a real reallocation of risk: it removes slab-leak exposure and makes a supply repair far cheaper, since nobody has to tunnel under the house or cut the slab. In exchange the pipe lives with attic heat, with ultraviolet light wherever daylight reaches, and with freeze exposure — and when a line lets go, water enters from above the finished ceiling rather than below the slab.
How to read the print string, and why the type letter is a distraction
PEX comes in three types, and the letter describes how the polymer was crosslinked, not a quality grade. PEX-A is crosslinked in the melt during extrusion by the peroxide or Engel method, and is the most flexible. PEX-B is crosslinked after extrusion by silane moisture cure; it is the most commonly manufactured type, stiffer, with coil memory. PEX-C is crosslinked after extrusion by electron-beam irradiation. All three must meet the same specifications — ASTM F876 for tubing and ASTM F877 for hot- and cold-water distribution systems.
The argument you hear in a showroom, or from a plumber quoting a re-pipe, is that one type resists chlorine better than another. That does not survive contact with the evidence. There is no neutral, primary, head-to-head comparison of PEX-A, PEX-B and PEX-C oxidative resistance; everything published comes from manufacturers with a commercial reason to prefer their own answer. Chlorine resistance is a property of the specific product's formulation and stabiliser package — verified by ASTM F2023 testing and printed on the pipe — not a property of the letter.
The chlorine rating, printed on the pipe
Uponor publishes the designations for its own pipe as follows:
- CL-0 — no rating.
- CL-1 — chlorinated water 25% of the time at 140°F and 75% of the time at 73.4°F.
- CL-3 — 50% of the time at 140°F and 50% of the time at 73.4°F.
- CL-5 — 100% of the time at 140°F with 4 parts per million chlorine.
CL-5 is the highest, and a CL-5 PEX-B and a CL-1 PEX-A are not comparable on the basis of the letter.
The UV rating, and why it is more serious than it sounds
The same print string carries a UV designation: UV-0 no rating, UV-1 one month, UV-2 three months, UV-3 six months. Those are months, not years. PEX is rated for a jobsite exposure window — the time between delivery and enclosure — not for permanent daylight. A run sitting in sunlight from a gable vent or an open soffit is exposed to something the product was never rated for, which turns a UV-exposed run from a pedantic note into a service-life question. Confirm the limit against the specific manufacturer.
CPVC, chemical incompatibility, and the spray foam collision
The dominant real-world CPVC failure mode is environmental stress cracking — the material crazes and cracks when under stress and in contact with an incompatible chemical, and the manufacturers document it at length. Charlotte Pipe's compatibility bulletin lists thread sealants and tapes not conforming to IAPMO PS 36; caulks and sealants with incompatible plasticisers or solvents; cutting oils, especially those marketed as environmentally friendly or vegetable based; leak-detection soaps, since most modern dishwashing liquids contain synthetic detergents the bulletin warns may cause stress cracking of fittings; termiticides and insecticides; and flexible plastics containing plasticisers.
One entry deserves its own paragraph here. Charlotte Pipe states that it does not recommend the use of polyurethane spray-on foam insulation in conjunction with its CPVC pipe and fittings. Read that against what is happening locally: attic encapsulation with closed-cell spray foam is being sold aggressively into exactly the 1990s housing stock that has CPVC running through the attic. The two collide house by house, and the homeowner is almost never told there is a manufacturer position on the combination. Before encapsulating an attic, establish what the supply lines up there are made of.
The other failure modes are age-related. Decades of attic temperature swings make older CPVC brittle, and it cracks at fittings, at supports, and wherever it is disturbed — which matters during a transaction, because aged CPVC can crack simply from being handled. Lubrizol's FBC System Compatible Program is where to check any product going near CPVC; the full incompatible list is in Charlotte Pipe's bulletin.
The PEX fitting lawsuits, and why they are over
PEX has been the subject of several class actions, and the detail that gets lost is that the tubing was generally not the primary defect claim — the fittings were. Many PEX crimp fittings made to ASTM F1807 were manufactured from yellow brass, a high-zinc alloy. In certain water chemistries yellow brass undergoes dezincification: zinc leaches selectively out of the alloy, leaving a weak, porous structure that can crack and leak and sheds corrosion product that restricts flow.
- In re Zurn Pex Plumbing Products Liability Litigation (D. Minn., No. 0:08-cv-01958) — Zurn yellow brass crimp F1807 fittings alleged to prematurely degrade, leak and cause damage through corrosion. A $20 million fund, final claim deadline April 1, 2020.
- In re Uponor, Inc., F1807 Plumbing Fittings Products Liability Litigation (D. Minn., MDL No. 11-MD-2247), preliminarily approved January 19, 2012, covering damage from leaks and decreased water flow. The order records only that plaintiffs contended the systems were defective; it makes no finding about a mechanism.
- Cole v. NIBCO, Inc. (D.N.J., No. 13-cv-7871) — NIBCO PEX 1006 tubing manufactured January 2005 to August 2012, F1807 fittings and stainless steel clamps. A $43.5 million fund with a six-year claim period; NIBCO disputed the allegations.
- Kitec, which has a Texas connection: the composite system sold as Kitec, PlumbBetter, IPEX AQUA, WarmRite, Kitec XPA, AmbioComfort, XPA and KERR Controls had its U.S. class certified by the United States District Court for the Northern District of Texas. A US$125,000,000 fund, claims deadline January 9, 2020. Dezincification is the universally reported cause, but the settlement's own materials state no mechanism.
Every one of those deadlines has passed. Like the polybutylene settlement before them, these are closed, and a homeowner who finds affected fittings today has no class remedy. None of it indicts PEX as a category: modern systems overwhelmingly use different fitting materials — dezincification-resistant and low-lead brass, engineered polymer fittings, or cold-expansion ASTM F1960 fittings. The closed-claim record is at the Kitec settlement FAQ.
What an inspector can and cannot determine
The Texas plumbing standard of practice, 22 TAC §535.231, draws the line clearly. An inspector shall report the visible material used for water supply lines — CPVC at the water heater, PEX in the attic, PB2110 at the meter; report as deficient visible deficiencies in those pipes, including cracks, leaks, damage, improper support, missing nail plates and ultraviolet-exposed runs; report static water pressure, and report as deficient pressure exceeding 80 PSI and the lack of a pressure reducing valve where it does; and report functional flow with two fixtures operated simultaneously, which is how a restriction from corroding fittings first shows itself.
An inspector cannot, and is not required to:
- Determine the PEX type or chlorine rating on concealed pipe. It is printed on the pipe; inside a wall it is unknowable.
- Determine the fitting alloy, or whether a fitting was covered by a settlement — that takes exposing and often destructively examining one.
- Determine water chemistry; §535.231(a)(2)(E)(i) excludes quality, potability and volume of the supply.
- Inspect concealed piping at all — §535.227 excludes anything buried, hidden, latent or concealed, which is most of a slab house's supply system.
Identifying fittings, scoping a re-pipe, pressure testing and any repair belong to a licensed plumber.
What people get wrong
"CPVC is defective like polybutylene." No, and this error drives unnecessary re-pipes. CPVC is a code-approved material still manufactured and installed today, with a long service record; its failures are a combination of age, chemistry and installation quality rather than a design defect. Polybutylene is a discontinued product with a closed class settlement behind it. Different stories.
"PEX was recalled." It was not, and neither was CPVC. Specific manufacturers' yellow brass F1807 fittings, and in one case specific tubing lots, were the subject of settlements between roughly 2012 and 2019, and all those windows are shut. Nor is PEX-A a grade above PEX-B: the letter is a manufacturing process, and on the question people care about the answer is printed on the pipe.
"My inspector should have told me what is in the walls." The rule says visible material and means it. In a slab house with an attic water heater and boxed-in stub-outs, an inspector may see almost nothing — a disclosed limitation, not an oversight.
And the finding people consistently under-react to: static pressure over 80 PSI. Cheap to correct, reportable as a deficiency, and it shortens the life of every plastic fitting in the house.
What to do about it
Visible CPVC in a 1990s house, no cracking and no repairs evident. Monitor, and open a budget line. This is an ageing system, not an emergency. Keep incompatible chemicals away from it, and do not let anyone foam the attic without a plumber's view on the pipe up there first.
A crack in aged CPVC, or evidence of prior CPVC crack repairs. Get it evaluated before closing. One crack in brittle decades-old CPVC is rarely the only one.
Spray foam encapsulation already over existing CPVC. Get it evaluated while a plumber's assessment can still change the deal.
PEX exposed to daylight at a vent or opening. Budget for it — the ratings are in months, so do not file it under cosmetic.
PEX with visible yellow brass fittings plus flow restriction or green and white corrosion product. Get it evaluated before closing. The settlements are closed, which means anything found is yours to pay for.
PEX, properly supported, no visible issues. Monitor. This is the current standard material installed correctly, and there is nothing here to negotiate. Static pressure over 80 PSI, though, should be corrected on any system.
Common questions
Is CPVC as bad as polybutylene?
No, and conflating the two is the most common error in local content on this subject. CPVC is a code-approved material that is still manufactured and still installed today. Its failures come from age, from contact with incompatible chemicals, and from installation quality — not from a design defect in the material itself. Polybutylene is a discontinued product with a national class settlement behind it, and that settlement is closed. If someone quotes you a whole-house re-pipe on the grounds that CPVC is defective, get a second opinion.
Is PEX-A better than PEX-B?
Not as a category. The letter tells you how the polymer was crosslinked, not how good the product is, and all three types must meet the same ASTM F876 and F877 requirements. On chlorine resistance specifically, there is no neutral head-to-head study — every comparison in circulation comes from a manufacturer of one type. What you can actually check is the print string on the pipe, which carries a chlorine-resistance designation from CL-0 through CL-5 based on ASTM F2023 testing. A CL-5 pipe of any type outperforms a CL-1 pipe of any other.
Can I still file a claim over PEX fittings?
No. All four of the major PEX fitting settlements have closed. The Zurn claim window ended April 1, 2020; the Kitec deadline was January 9, 2020; the NIBCO and Uponor programmes have likewise run their course. A homeowner who discovers affected yellow brass F1807 fittings today has no class remedy and pays for the work. That is the practical reason to look at fittings during the option period rather than after closing.
Does spray foam insulation damage CPVC pipes?
The manufacturer's own position is that the combination is not recommended. Charlotte Pipe states that it does not recommend the use of polyurethane spray-on foam insulation in conjunction with its CPVC pipe and fittings, and CPVC is known to be vulnerable to environmental stress cracking from contact with incompatible chemicals. This matters more in North Texas than almost anywhere, because retrofit attic encapsulation is being sold into the same 1990s houses that have CPVC running through the attic. Establish what the supply lines are made of before anyone sprays anything.
How long do CPVC and PEX supply lines last?
There is no honest single number, and anyone who gives you one is guessing. Service life depends on water chemistry and disinfectant residual, on operating temperature and pressure, on ultraviolet exposure, on the specific product's stabiliser package, and on how well it was installed. What you can control is the short list of things that measurably shorten it: static pressure over 80 PSI, daylight on the pipe, and contact with incompatible chemicals in the CPVC case. Fix those and the question becomes much less interesting.
Are supply lines in the attic worse than under the slab?
They are different, not worse. Overhead runs eliminate the slab-leak scenario entirely, and a repair costs a fraction of tunnelling under a house or cutting a slab. In exchange, the pipe lives in a North Texas attic, with the heat, the freeze exposure and the ultraviolet light that come with it, and a failure sends water down through a finished ceiling instead of into the soil. On balance most inspectors would rather have the overhead run, provided it is properly supported, protected at framing penetrations, and out of direct daylight.