Water Supply & Distribution
Water supply systems including pipe materials, sizing, pressure, valves, and residential water service.
- Compare copper, PEX, CPVC, and other water supply pipe materials
- Calculate water supply sizing based on fixture units and demand
- Identify valve types and their correct applications
- Describe pipe support spacing and insulation requirements
Leçon 1
Pipe Materials - Copper, PEX, CPVC & More
Choosing the Right Material
Water supply piping must be approved for potable water service and suitable for the operating temperature and pressure of the system. The NPC recognizes several materials, each with distinct properties.
Copper
Type L - standard for water supply
Type M - lighter wall, limited use
Type K - heaviest, underground service
Joining: Soldering, brazing, press-fit
PEX (Cross-linked Polyethylene)
Flexible - fewer fittings needed
Freeze resistant - expands without splitting
Joining: Crimp, expansion, push-fit
Cannot be exposed to UV light
Copper Types Explained
Type L copper is the standard for interior water supply piping. The letter designation refers to wall thickness:
- Type K - thickest wall, green stripe, used for underground water service and high-pressure applications
- Type L - medium wall, blue stripe, standard for interior supply and some underground use
- Type M - thinnest wall, red stripe, limited to low-pressure interior applications where code permits
Exam Tip
Remember copper types by K-L-M - thickness decreases alphabetically. Type K is thickest (underground), Type M is thinnest (limited interior use).
CPVC and Other Materials
CPVC (Chlorinated Polyvinyl Chloride) handles higher temperatures than regular PVC, making it suitable for hot water supply. Galvanized steel was once standard but is rarely used in new construction due to corrosion and scaling issues. Stainless steel is used in specialized applications like medical facilities.
Type L copper is the standard water supply pipe. Copper types decrease in wall thickness from K (thickest) to M (thinnest). PEX is flexible and freeze-resistant but cannot be exposed to UV light. Always verify material approval for the specific application.