Use PVC for cold water under pressure and for drain, waste and vent piping. Use CPVC where the line carries hot water: Charlotte Pipe rates PVC to a maximum operating temperature of 140°F and FlowGuard Gold CPVC to 180°F. The two materials do not share sizing or solvent cement, so they are not interchangeable mid-run.
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One letter separates the two names and almost everything else about them is different: the temperature they survive, the outside diameter of the pipe, the can of cement that bonds it, and the part of the house they belong in. Get the pair confused on a repair and the joint either fails or never bonds at all.
What Is PVC Pipe?
PVC is polyvinyl chloride. The pressure-rated version is made to ASTM D1785, a specification that covers PVC pipe “made in Schedule 40, 80, and 120 sizes and pressure-rated for water.” It is the rigid white or gray pipe on cold supply, irrigation, pool and utility lines.
The same white Schedule 40 pipe also does drainage duty. Charlotte Pipe’s Schedule 40 listings are dual-marked to ASTM D1785 and ASTM D2665, the drain, waste and vent standard, which is why one pipe covers both the sink trap arm and the sprinkler main. If you are picking between drainage plastics, see PVC vs ABS pipe.
What Is CPVC Pipe?
CPVC is the same base polymer taken through additional chlorination, which raises the temperature it tolerates. It comes in two families. Copper tube size CPVC is made to ASTM D2846, whose components are “intended for water service up to and including 180 °F (82 °C)” and are produced “in one standard dimension ratio.” That is the tan pipe sold as FlowGuard Gold.
The second family is Schedule 40 and Schedule 80 CPVC, covered by ASTM F441, which covers CPVC pipe “made in Schedule 40 and 80 sizes and pressure-rated for water.” That material carries PVC’s dimensions with CPVC’s heat tolerance and shows up in industrial and hot-process work rather than in houses.
CPVC vs PVC: Which One Can Carry Hot Water?
This is the deciding question, and the manufacturer answers it directly. Charlotte Pipe’s plastics technical manual publishes maximum operating temperatures by system: ABS 140°F, PVC 140°F, FlowGuard Gold CPVC copper tube size 180°F, and Corzan CPVC Schedule 80 200°F.
A residential water heater set at 120°F to 140°F sits at or above PVC’s published ceiling before anything goes wrong. A stuck thermostat or a heat trap failure pushes it past. CPVC has headroom there; PVC does not. That single line in the table is the reason hot water distribution is CPVC and not PVC.
Temperature and Pressure Ratings
Both plastics lose pressure capacity as they warm, and the manual gives correction factors to multiply against the pipe’s rating at 73°F. PVC runs 1.00 at 73°F, 0.62 at 100°F, 0.40 at 120°F and 0.22 at 140°F, and is listed NR — not rated — at every temperature above that. CPVC runs 0.82 at 100°F, 0.65 at 120°F, 0.50 at 140°F, 0.25 at 180°F and 0.20 at 200°F.
Put numbers on it. Charlotte lists 1/2-inch Schedule 40 PVC at 600 psi at 73°F. Apply the manual’s own method at 140°F and that pipe is down to 132 psi. The pipe has not changed; the duty has. Cold service is where PVC keeps the rating you bought it for.
Sizing: IPS vs Copper Tube Size
The fittings do not cross over, and the reason is dimensional. Charlotte lists 1/2-inch Schedule 40 PVC at an average outside diameter of 0.840 inch. Half-inch CPVC copper tube size pipe under ASTM D2846 has an average outside diameter of 0.625 inch with a 0.068 inch minimum wall, rated 400 psi at 73°F.
Two pipes both called half inch, two different outside diameters. A PVC socket fitting will not grip CPVC copper tube size pipe, and forcing one on produces a joint with no interference and no bond line. Schedule 40 and 80 CPVC is the exception: it follows iron pipe size dimensions, so it matches PVC’s geometry while keeping CPVC’s temperature rating.
Working with plastic pipe for a living?
Solvent Cement and Primer
Cements are specified separately by material. ASTM D2564 “covers requirements for poly(vinyl chloride) (PVC) solvent cements to be used in joining poly(vinyl chloride) piping systems.” ASTM F493 does the same job for CPVC pipe, tubing and socket fittings. Primers under ASTM F656 are written for PVC pipe joined with D2564 cements.
In practice: PVC cement on CPVC is not a shortcut, it is the wrong product. For PVC work the two-step route is primer then cement — the Oatey 30246 PVC clear cement and NSF purple primer handy pack is the pairing most of us carry. For CPVC, orange cement such as Oatey 31128 medium CPVC cement is the match.
Whether an inspector wants primer under that joint depends on your adopted code and, for CPVC, on the color of the can. We walk through the rule and the exceptions in is purple primer required.
Where Each One Is Used in a House
PVC handles drain, waste and vent lines, the cold side of an irrigation system, pool and equipment piping, and buried cold supply where code permits. CPVC handles hot and cold potable distribution — the branch lines feeding fixtures and appliances.
One transition detail worth knowing: Charlotte Pipe notes that CPVC can be used with standard brass ferrules for compression connections where the operating temperature will not exceed 140°F, and advises PTFE tape over the ferrule to allow for the different expansion rates of metal and plastic. That is the stop-valve connection under a lavatory, and it is where a lot of CPVC gets damaged.
Cutting and Working the Two Materials
Both materials cut the same way, which is the one place they overlap cleanly. A ratcheting plastic tubing cutter takes either — the Klein Tools 50063 ratcheting PVC pipe cutter is listed for PVC, CPVC and PEX. Deburr and chamfer the cut end before cementing; a square, chamfered end is what lets cement stay in the joint instead of scraping off on entry. More options in our guide to the best pipe cutters.
Which Should You Buy?
Repairing or extending a drain, vent, irrigation or pool line: PVC, Schedule 40 unless the drawing calls for 80. Repairing or extending a hot or cold water branch inside the house: CPVC copper tube size, matched to whatever is already in the wall. Repiping a whole house from scratch: read PEX vs copper vs CPVC first, because the choice is rarely CPVC once the wall is open.
The one answer that is never right is mixing them in a supply run because the fittings looked close. They are not close, and the failure shows up as a weep months later rather than at the pressure test.
FAQ
Can PVC be used for hot water? No. Charlotte Pipe’s technical manual lists PVC’s maximum operating temperature as 140°F and shows PVC as not rated for pressure above that, while a residential water heater commonly runs at or near that figure. Hot water distribution is CPVC, PEX or copper.
Is CPVC pipe the same size as PVC pipe? Not in the residential form. Half-inch copper tube size CPVC has an average outside diameter of 0.625 inch, against 0.840 inch for half-inch Schedule 40 PVC. Schedule 40 and 80 CPVC under ASTM F441 does share PVC’s iron pipe size dimensions.
Can I use PVC cement on CPVC pipe? No. ASTM D2564 cements are specified for PVC piping systems and ASTM F493 cements for CPVC pipe, tubing and fittings. Match the cement to the material, and check the can lists your pipe size range.
How hot can CPVC get? Copper tube size CPVC components under ASTM D2846 are intended for water service up to and including 180°F. Charlotte Pipe lists 180°F as the maximum operating temperature for FlowGuard Gold CPVC and 200°F for Corzan CPVC Schedule 80, with pressure de-rated at both.
Is CPVC or PVC better for a repair? Neither is better in the abstract. The right one is whatever the existing line is, joined with its own cement. Cutting a CPVC branch and splicing PVC into it produces a joint that cannot bond and a pipe that is not rated for the water going through it.
Bottom Line
PVC is a cold-service and drainage pipe with a published 140°F ceiling. CPVC is a hot and cold distribution pipe rated to 180°F in its copper tube size form. They use different outside diameters, different fittings and different solvent cement, and the only thing they safely share is the cutter. Identify what is already in the wall before you buy anything.
Sources
- ASTM D1785 — Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120 (scope).
- ASTM D2846/D2846M — CPVC hot- and cold-water distribution systems (scope, 180 °F service).
- ASTM F441/F441M — CPVC plastic pipe, Schedules 40 and 80 (scope).
- ASTM D2564 and ASTM F493 — solvent cements for PVC and for CPVC; ASTM F656 — primers.
- Charlotte Pipe Plastics Technical Manual — maximum operating temperatures and de-rating factors (p. 29), Schedule 40 PVC dimensions (p. 21), CPVC copper tube size dimensions (p. 28), CPVC compression connections (p. 65). Figures read September 2026.
Related guides
- PVC vs ABS pipe
- PEX vs copper vs CPVC
- Is purple primer required?
- The best pipe cutters
- The best pipe repair clamps
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