5.3 Water Service and Distribution Materials & Joints

5.3 Water Service and Distribution Materials & Joints

Commercial plumbing systems rely on a variety of piping materials, each approved for specific temperature, pressure, and chemical environments. The International Plumbing Code (IPC) Section 605 governs the selection of piping materials, approved joining methods, dielectric separation, flushing/disinfection, and pressure testing requirements.

Water Service vs. Water Distribution

The code maintains a strict distinction between the piping outside the building and the piping inside the building:

1. Water Service Pipe: The pipe from the water main or other source of potable water utility supply to the water meter or the point of entry into the building foundation.
2. Water Distribution Pipe: The piping inside the building that conveys water from the water service pipe (or building entry point) to the individual fixtures, appliances, and outlets.

Material Standards (IPC Table 605.3 & Table 605.4)

Piping materials must be listed and certified to specific standards.

Copper Tubing (ASTM B88)

Copper is categorized by wall thickness, which determines its allowable location:

• Type K (Thickest wall): Approved for both underground water service and interior water distribution. It is highly resistant to soil corrosion and mechanical damage, making it the standard for underground service entry.
• Type L (Medium wall): Approved for water distribution inside the building. It is the most common commercial distribution material.
• Type M (Thinnest wall): Approved for water distribution, but prohibited for underground water service in almost all jurisdictions.
• Type DWV (Thinnest copper): Prohibited for water supply; approved only for drainage, waste, and vent systems.

Plastic Materials

• CPVC (ASTM D2846): Chlorinated Polyvinyl Chloride is approved for both hot and cold water distribution inside buildings. It has a high temperature rating.
• PEX (ASTM F877 or CSA B137.5): Crosslinked Polyethylene is approved for hot/cold water distribution. It must be protected from ultraviolet (UV) light exposure during storage and installation to prevent material breakdown.
• PVC (ASTM D1785): Polyvinyl Chloride is approved for underground water service (cold water only) but is strictly prohibited for water distribution inside the building because it cannot handle high temperatures and can shatter explosively under air pressure.
• PP-R and PP-RCT (ASTM F2389): Polypropylene is increasingly used in commercial distribution. It is joined by heat fusion, which creates seamless leak-free joints.

Approved Joint Connections and Galvanic Corrosion

The code requires joints to be made using approved procedures to maintain flow and prevent leaks.

• Solder Joints (Copper): Solder and flux used in potable water systems must be lead-free, which the code defines as containing not more than 0.2% lead (IPC Section 605.14.3). Flux must conform to ASTM B813.
• Mechanical Press Joints: Press-connect fittings (e.g., ProPress) are approved for copper and stainless steel piping when installed with the manufacturer's tooling and matching gaskets.
• PEX Joints: Must use mechanical crimp rings, cinch clamps, or cold-expansion sleeves conforming to ASTM F1807 or ASTM F1960. Solvent cement is never permitted on PEX.
• Galvanic Corrosion (Dissimilar Metals): When copper or brass is connected directly to steel or iron piping, galvanic corrosion occurs due to the difference in electrical potential, leading to rapid corrosion of the steel/iron. The code requires the use of dielectric unions or brass/bronze transition fittings to physically isolate the dissimilar metals.

Shutoff and Isolation Valves (IPC Section 606)

To allow for maintenance and emergency isolation:

• Water Service Entrance: A full-open shutoff valve (such as a ball valve or gate valve) must be installed on the water service pipe at the point of entry into the building.
• Water Heaters: A full-open shutoff valve must be installed on the cold water supply pipe to each water heater.
• Individual Fixtures: Shutoff valves (fixture stops) must be installed at each fixture in commercial buildings to allow isolation without shutting down the entire branch. Exception: Fixture stops are not required at individual showerheads or bathtubs.

Potable Water System Disinfection (IPC Section 610)

Before a new or modified commercial potable water system is put into service, it must be disinfected to remove bacteriological contamination. The standard procedure requires:

1. Flushing: The system must be flushed with potable water until dirty water is cleared.
2. Chlorination: The system must be filled with a chlorine solution of:
   • Minimum 50 parts per million (ppm) for a contact time of at least 24 hours, OR
   • Minimum 200 parts per million (ppm) for a contact time of at least 3 hours.
3. Final Flush: The chlorinating agent must be flushed out of the system until the residual chlorine matches the municipal supply level.
4. Testing: Water samples must be taken and tested by an approved laboratory to verify the absence of coliform bacteria.

Pressure Testing (IPC Section 312.5)

Potable water service and distribution piping must be pressure tested to ensure mechanical integrity.

• Test Pressure: Not less than 100 psi or the working pressure of the system, whichever is greater.
• Medium: Water (hydrostatic test) is the standard. Air testing is permitted only if the pipe material is rated for air testing (e.g., copper or PEX). PVC and CPVC must never be pressure tested with compressed air because they can shatter violently and cause injury.
• Duration: The test must be held for at least 15 minutes with no drop in pressure or visible leaks.