PEX, Copper, or CPVC: A Homeowner's Guide to Pipe Choices
Three of the most common water supply pipes, three different sweet spots. A homeowner's guide to picking, or evaluating what a plumber proposes.
PEX (cross-linked polyethylene)
• Flexible, runs through framing with fewer joints
• Three subtypes: PEX-a (most flexible, repair-friendly), PEX-b (most common, cost-effective), PEX-c (slightly less flexible)
• Several fitting systems: cold-expansion (Uponor ProPEX), crimp, clamp, push-fit
• Best for: new construction, repipes, where flexibility through walls matters
• Caveats: UV-sensitive (don't expose to sunlight), some PEX is rated for hot water service, some isn't — read the label
Copper
• The traditional choice, soldered or pressed (Viega ProPress)
• Long-proven lifespan in most water chemistries
• Type L is standard for residential; Type M is thinner and acceptable in many jurisdictions
• Best for: visible runs (cleaner aesthetic), service entries, repair sections
• Caveats: cost, susceptibility to pinhole leaks in aggressive water chemistries, theft risk in vacant homes
CPVC
• Heat-resistant cousin of PVC, solvent-welded
• Common in production homes (FlowGuard Gold is the dominant brand)
• Less flexible than PEX but cheaper than copper
• Best for: cost-conscious new builds, retrofits where solvent welding is acceptable
• Caveats: brittle when cold, sensitive to certain construction adhesives, fitting failures more common than PEX
What this means for you
For a new home or a major repipe, PEX-a is usually the default for good reason. Copper still wins on aesthetics for visible work and on durability in service entrances. CPVC is fine when it's done well but doesn't have PEX's flexibility advantage.
What contractors should know
The pipe choice is part of the proposal, not a hidden detail. Stating it clearly avoids confusion when the homeowner sees pink and blue lines instead of copper.
The part nobody can see later
Most of what decides how this holds up gets covered before the job is over. Once it is closed in, the only record of how it went in is the photos taken while it was still open.
Supervisr's Plumbing QA model works from common industry practice and the installation instructions that ship with the materials. It can evaluate plumbing installation photos for pipe support and slope, joining quality, vent stack configuration, water heater install (TPR, expansion tank, drain pan), and backflow protection. Upload photos of supply pipe support spacing, DWV slope and venting, water heater TPR discharge and drain pan, backflow device install orientation, joining quality (sweat, crimp, expansion), and you'll get a documented evaluation back in minutes.
For a homeowner, that record is a straightforward way to understand what you paid for. For a contractor, it is the milestone documentation that stands behind a workmanship warranty years later, long after the crew has moved on to the next job.
About Supervisr
Supervisr is an AI quality-assurance platform for residential plumbing. It works from common industry practice and manufacturer installation instructions, and evaluates plumbing installation photos against published install references.
Contractors use Supervisr to document quality at each milestone — backing up a workmanship warranty and building a track record of work they can point to. Homeowners end up with a clear record of what went into their home. See how it works at supervisrapp.com.