Code Library
Water Supply and Pipes: Rules in Phoenix-Area Cities
Water service lines, meters, pressure, shutoff valves, pipe materials and sizing. City by city, then the Arizona law and model code behind it.
Uniform Plumbing Code
All UPC sections- Model Code · Updated Jul 2026UPC 606: Where Shutoff Valves Are RequiredUPC Section 606 sets where the water supply system needs valves. The main building supply needs a full-way valve so the whole structure can be shut off in one place. Each dwelling unit in a multi-unit building gets its own control valve. The section also covers valves for groups of fixtures, where a check valve is required, and a draindown valve.
- Model Code · Updated Jul 2026UPC 609: Water Piping Installation and TestingUPC Section 609 sets how potable water piping is installed, supported, protected, and tested. New water lines must be supported at set spacing and shielded where they could be damaged. Before the system is covered, it must pass a pressure test. The plumber holds the pipe at working pressure with water, or at 50 psi with air, for 15 minutes with no leaks.
- Model Code · Updated Jul 2026UPC Section 313: How Often a Pipe Must Be SupportedUPC Section 313 sets how often plumbing pipe must be held up by hangers or supports so it cannot sag, strain its joints, or trap water. The required spacing depends on the pipe material and whether the run is horizontal or vertical, with softer materials like PEX needing more frequent support.
- Model Code · Updated Jul 2026UPC Section 604: Approved Materials for Water PipeUPC 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.
- Model Code · Updated Jul 2026UPC Section 720: The Required Gap Between Water and Sewer LinesUPC Section 720 requires a water service line to stay at least 10 feet horizontally from a building sewer or septic line. When that gap is not possible, the water line must sit on a solid shelf at least 12 inches above the sewer, so a sewer leak cannot reach the drinking water.
- Model Code · Updated Jul 2026UPC Water Supply Pipe Sizing: How Code Sizes Your Water LinesThe Uniform Plumbing Code sizes water supply pipe so every fixture gets enough flow and pressure at once. It counts each fixture's demand in water supply fixture units, adds them up for a line, and factors in pipe length and available pressure to set the minimum pipe diameter.
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