UPC Section 604 lists which pipe materials are approved for a building's water service line and interior water distribution. Only listed materials rated for potable water and pressure may be used, such as copper, PEX, CPVC, and approved plastics, each installed by the rules for that material.
The Uniform Plumbing Code is published and copyrighted by IAPMO. This page explains the section in our own words with a short excerpt only. Read the full official text at the source.
The pipe that carries drinking water into and through a home cannot be just any pipe. It has to be safe for potable water, able to hold pressure, and durable in the ground or the wall. UPC Section 604 and the related materials rules list exactly which pipe materials are approved for the water service line, the pipe from the meter to the house, and for the water distribution system inside the house.
What this section says
The code approves a specific set of materials and rejects the rest. The governing idea is that every material has to be listed for potable water use and installed to its own standard. The code frames it this way:
Pipe, tube, and fittings used in a potable water system shall be of an approved material and shall conform to the applicable standards.
The commonly approved materials for water service and distribution include copper, PEX (cross-linked polyethylene), often run from a PEX manifold, CPVC (chlorinated PVC), and other listed plastics and metals. Each carries its own rules. Copper has to be the right type for the job. PEX and CPVC must be listed for hot water where they carry it, and joined with approved fittings. Underground service pipe has to resist the soil it sits in. Plain PVC, which is fine for drains, is not approved for pressurized hot water distribution. The point of the list is that a material approved for one use is not automatically approved for another.
When this comes into play
This section governs every new water line and every repipe. Picture a homeowner repiping an old house: the choice between copper, PEX, and CPVC is not just about cost, it is about which materials code approves for that use and how each must be installed. An inspector checks that the pipe is a listed material, joined correctly, and rated for the water it carries. Using an unapproved or mismatched material is a common reason a repipe fails inspection.
What this means for you
If you are choosing pipe for a repipe or an addition, start from the list of what code approves, then weigh cost and longevity within that list. The material affects price, lifespan, and how the water tastes and flows. For a direct comparison of two popular choices, see PEX vs CPVC pipe and whole-house repipe cost, PEX vs copper. How that approved pipe must be run and tested is covered in UPC 609 water piping installation. Because material and installation both have to meet code, a licensed plumber pulling the permit is the safe path on a repipe.
Full text and source
UPC Section 604 is part of the Uniform Plumbing Code. IAPMO publishes and holds the copyright on it. The excerpt above reflects the rule as adopted; Phoenix enforces the 2024 UPC with local amendments, so verify the current approved-materials list and section numbers. Read the water-service rules on UpCodes, or confirm local amendments through the City of Phoenix: phoenix.gov/pdd.
Keep Reading
- UPC Section 313: How Often a Pipe Must Be Supported
- UPC Water Supply Pipe Sizing: How Code Sizes Your Water Lines
- UPC 1003: Which Fixture Traps Are Allowed (and Banned)
- UPC 1007: Trap Seal Protection for Floor Drains
- PEX vs CPVC pipe: which is better?
- What does a whole-house repipe cost, and is PEX or copper better?
- Do I have polybutylene pipes, and should I replace them?