Approved Materials and Listed Products: Pipe, Fittings, and Jointing Methods

Why Approved Materials Matter

Every pipe, fitting, and joint installed in a building must be listed and approved under the plumbing code in force for that jurisdiction. Using an unapproved material can result in a failed inspection, a required tear-out, liability for water damage, and — in the case of potable water systems — a genuine public-health hazard. Both the International Plumbing Code (IPC) and the Uniform Plumbing Code (UPC) contain dedicated chapters that list acceptable pipe materials, the fittings allowed with each, and the jointing methods permitted. Your job as a plumber is to read those tables before you purchase materials, not after the inspector arrives.

How the Codes Organize Approved Materials

Both codes group approvals by application:

• DWV (Drain, Waste, and Vent) systems carry wastewater and sewer gases away from fixtures.
• Water-supply (potable and non-potable) systems deliver water under pressure to fixtures.

A material approved for DWV is not automatically approved for water supply, and vice versa. Always check the correct table for the correct application.

Both codes also require that pipe and fittings be listed — meaning tested and certified by a recognized third-party organization such as NSF International, UL, or IAPMO's listing program. The listing standard (for example, NSF/ANSI 61 for potable-water contact materials) is printed in the code table alongside the material. If a product carries that listing mark, it has met the chemical and mechanical requirements of that standard.

Common Pipe Materials and Their Permitted Applications

ABS (Acrylonitrile Butadiene Styrene) — black rigid thermoplastic. Permitted for DWV above ground and underground in both IPC and UPC. Not permitted for water supply. Joined by solvent cement specific to ABS; ASTM D2235 solvent cement is the type referenced in the codes.

PVC (Polyvinyl Chloride) — white or cream rigid thermoplastic. Schedule 40 and Schedule 80 are common wall thicknesses. Permitted for DWV in both codes. Also permitted for cold-water supply in both codes (not hot water supply). Joined by PVC solvent cement; mixing ABS cement with PVC pipe or fittings is a code violation.

Copper — the most broadly permitted material in both codes. Type K, L, and M copper tube are permitted for water supply (above and below ground, hot and cold) and for DWV. Type DWV copper is a lighter wall approved for drain and vent only. Joining methods include soldered (sweated) joints, brazed joints, and press-connect fittings listed for the application. Lead-free solder (not more than 0.2% lead) is required by federal law for potable water; never use 50/50 tin-lead solder on drinking water piping.

Cast Iron — gray or ductile iron. Permitted for DWV in both codes; widely used for large-diameter drain and sewer lines because of its noise-dampening properties and durability. Joined by hub-and-spigot with compression gaskets or no-hub couplings (banded couplings meeting the applicable CISPI or ASTM standard). Not permitted for pressurized water supply.

CPVC (Chlorinated Polyvinyl Chloride) — cream or light yellow rigid thermoplastic. Permitted for both hot and cold water supply in both IPC and UPC. Also permitted for DWV in some jurisdictions. Requires CPVC-specific solvent cement; do not use standard PVC cement on CPVC. Temperature and pressure ratings are higher than PVC, which is why it can handle hot-water distribution.

PEX (Cross-Linked Polyethylene) — flexible tubing, color-coded red (hot), blue (cold), and white (either). Permitted for hot and cold water supply in both IPC and UPC. Not permitted for DWV under either code. Joined by crimp rings, clamp (cinch) rings, or expansion fittings, depending on the system type (PEX-A, PEX-B, or PEX-C). PEX cannot be used outdoors where exposed to UV light unless listed for that purpose.

Galvanized Steel — steel pipe with a zinc coating, threaded and joined with threaded fittings. Both codes permit it for water supply (hot and cold), though its use has declined sharply because the zinc lining corrodes and reduces flow over time. Not permitted for new DWV installation under the IPC; the UPC similarly restricts its DWV use. Always use the correct pipe joint compound or PTFE tape rated for potable water.

Jointing Methods and Listed Fittings

The fitting must be listed for the same material and application as the pipe. Key rules:

• Solvent-cemented joints: the cement must match the pipe material. Primer is required with PVC and CPVC in most code editions before cementing.
• Soldered/brazed joints: flux must be water-soluble, lead-free flux listed for potable water. Flux left in the pipe promotes corrosion; flush the system after work.
• Mechanical joints (press, push-fit, compression): must be listed for the operating pressure and temperature of the application. Push-fit fittings are not always permitted underground — check the listing.
• Transition fittings: when two different materials meet (e.g., copper to PEX), a listed transition fitting is required. Dielectric unions are required where galvanized steel connects to copper to prevent galvanic corrosion.

Safety Points

• Chemical burns: solvent cements and primers contain volatile organic compounds. Work in ventilated areas, wear safety glasses and chemical-resistant gloves.
• Burns from soldering: use flame-resistant barriers to protect framing; keep a fire extinguisher nearby. Allow joints to cool before handling.
• Lead exposure: dispose of old lead-tin solder waste properly; wash hands before eating or drinking.
• Lockout/tagout: before working on any existing system, shut off and lock out the water supply and — where applicable — depressurize the line before cutting.

Reading the Code Tables

When you open the approved-materials chapter in either code, you will find a table with columns for material name, applicable standard (e.g., ASTM, AWWA, or NSF designation), and permitted use. The section and table number differ between IPC and UPC editions, so always note which code and which edition year applies in your jurisdiction. On the exam and on the job, citing the section number proves you looked it up rather than guessed.