Installation of Water Supply and Distribution Piping Systems
Water supply and distribution piping
This domain tests layout, sizing, pressure, valves, supports, and testing of cold and hot water systems. You need to show that water reaches each fixture at adequate pressure without noise or contamination.
Core rules
- Size by fixture units and developed length; keep velocity within normal limits to reduce noise and erosion.
- Provide isolation valves at the main, each riser, and each fixture group; install check valves and backflow protection where required.
- Support pipe at approved spacing; allow for expansion on hot lines.
- Install air chambers or water-hammer arrestors at quick-closing valves.
- Slope horizontal runs slightly to drain and provide drain valves at low points.
- Test before closing walls: hydrostatic test at the specified pressure, commonly 1.5 times working pressure or a minimum stated in the specification, held for the required duration.
Worked example
A ground-floor source reads 300 kPa. A fixture is 10 m above the source, so static loss = 10 × 9.81 ≈ 98 kPa. Estimated friction loss is 40 kPa. Residual pressure = 300 − 98 − 40 = 162 kPa. If the fixture needs 100 kPa, the result is acceptable. The reasoning separates elevation loss from friction and compares the residual with the fixture requirement.
Traps
Confusing static and flowing pressure, ignoring elevation, omitting a valve or arrestor, testing with air instead of water where water is specified, and failing to flush debris before fixture connection are common errors.