In the Field · Part 4
Materials and methods: PEX vs. copper vs. CPVC, ABS vs. PVC (it is regional), cast iron, and the transitions that fail
Every material a plumber runs is approved somewhere in the code's tables, and every one has a place where it fails: PEX at the water heater, copper at the galvanized nipple, ABS glued to PVC with the wrong cement, cast iron cut without a shielded coupling. This lesson is the working comparison a contractor needs to choose and to price: supply in PEX, copper, or CPVC; drainage in ABS, PVC, or cast iron; where the state code draws its lines (PEX not within 18 inches of the heater, dielectric transitions, listed transition fittings), where the regional convention decides (ABS in most of California's residential work, PVC in some jurisdictions and most commercial), and where a city's amendment overrides all of it.
What the full lesson covers
- Supply: PEX is the repipe default for cost and speed, run in a manifold or trunk-and-branch, with the code's limits (not within 18 inches of a water heater; PEX-AL-PEX not adopted for potable water in California); copper remains the standard for exposed work, heater connections, and jurisdictions or customers that want it; CPVC is lawful and less used.
- Every copper-to-steel joint is a dielectric transition: a copper alloy adapter, a 6-inch copper alloy nipple, or a listed dielectric union or fitting (CPC 605.16.1). Skip it and the galvanic joint fails in years.
- Drainage: ABS and PVC are both approved by Table 701.2; which one a region uses is convention and local amendment, and the two are joined only with a listed transition fitting or cement, never with ordinary ABS or PVC cement (605.16.2, 705).
- Cast iron is cut with a snap cutter and joined with shielded, listed couplings; a no-hub band on old bell-and-spigot is a leak. In plenums outside single-family dwellings, plastic DWV must meet the flame and smoke limits or be run in metal.
- Read the city's amendment list before the takeoff; a material the state approves may be restricted where the job is.
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More lessons in The Field: Method, Code, and Cases
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- 2Permits: when one is required, what is exempt, pulling it online, the inspection sequence, what inspectors look for, and handling corrections
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- 7Sewer and drain I: the camera, the locator, hydro-jetting vs. cabling, and when each is the right tool
- 8Sewer and drain II: trenchless vs. open trench, whose lateral it is (it varies by city), backwater valves, and point-of-sale lateral ordinances
- 9Case: the hissing line. The meter test, the supply leak that fed the roots, the lateral to the city tap, and the contract and permit trail
- 10Leak detection: slab leaks, acoustic and pressure methods, thermal imaging, and repipe vs. reroute
- 11Low pressure: the PRV, galvanized pipe, and the sequence that finds which one it is
- 12Sewer gas: trap seals, trap primers, vents, and the sequence that finds the smell
- 13Water treatment: where softeners are restricted in California, filtration, pressure regulators, and thermal expansion
- 14Fixtures and conservation: CALGreen flow rates, SB 407 retrofit-on-alteration and disclosure-on-sale, 1.28 gpf, and the ADA basics a plumber needs
- 15Materials and methods: PEX vs. copper vs. CPVC, ABS vs. PVC (it is regional), cast iron, and the transitions that failYou are here
- 16Commercial basics: grease interceptors, the backflow program, and the tester certification that opens a second line of work
- 17Cal/OSHA for a small shop: the IIPP every employer must have, heat illness prevention, trenching and the 5-foot permit, confined space, silica, and ladders
- 18Environmental rules: EPA lead-safe certification for any pre-1978 home, asbestos and transite pipe, and stormwater
- 19Job-site craft: sequencing with the other trades, protecting the home, and the punch list that ends the job
- 20Case: the water heater that failed inspection twice
- 21Case: the gas leak call. The protocol, and the walk-away
- 22Case: the "customer doesn't want a permit" job
- 23Template: the job-site checklist, from the truck to the walk-through
- 24Template: the pre-inspection checklist by stage. Underground, rough, water heater final, gas, and trim
- 25Template: the Injury and Illness Prevention Program starter for a plumbing shop of one to five
- 26Template: the Heat Illness Prevention Plan for a plumbing shop, outdoor and indoor
- 27Template: the customer options sheet (good / better / best) with the cost band, the permit path, and the code trail on each rung