Domestic Water System Notes

Domestic Water System

The IPC (International Plumbing Code) addresses domestic water supply and distribution systems.
Objective: Understand system components, locations, routing, and fixture connections.

To determine water tower height for a specific pressure: Height \times 0.433 = PSI, or PSI / 0.433 = Height.
Example: 96 PSI requires a water tower height of 96 / 0.433 = 221 feet.

Components include the water service pipe, distribution pipes, fittings, control valves, and appurtenances.
Key parts: Corporation stop, curb stop, water meter, and service valve.
Water service pipe connects the water main to the building's distribution system.

Coordinate with the municipal water supplier for installation requirements, meter details, and allowed piping materials.

IPC 603.2 requires separation between the building sewer pipe and the water supply pipe.
A 5-foot horizontal separation is needed if in separate trenches.
No separation is required if the water service pipe is 12 inches above the sewer.
If crossing, the water service pipe must be sleeved 5-feet either side of the sewer.

IPC 608 mandates protection against contamination using backflow preventers at each opening/connection.
A point-of-source backflow preventer is typically needed at the service entrance.
Local standards dictate backflow preventer requirements.

Reduced Pressure Principle Backflow Preventer (RPZ): Highest level of protection.
Double Check Valve Assembly: Similar to RPZ but lacks a relief valve.
Vacuum Breaker Assembly: Uses atmospheric pressure to prevent backflow.
Dual Check Valve: For small applications; may be restricted by local codes.
Air Gap: Achieves backflow prevention through physical separation.

Used to isolate water system components for service or emergencies; must be fully open or closed.
Types: Ball, gate, and butterfly閥.
Ball valves can cause water hammer due to quick shutoff.
Globe valves close slowly, preventing water hammer; better for flow adjustment.
Gate valves are suitable for larger (2"+) service entries to avoid hammer.

On the building water service pipe near the curb.
At the water distribution supply pipe's entrance to the structure.
On the discharge side of every water meter.
At the base of water riser pipes (except in some residential buildings).
At the top of water down-feed pipes (except in some residential buildings).
At the entrance to every dwelling unit's water supply (except for single fixture supplies with individual stops).
On the water supply pipe to gravity or pressurized (hydropneumatic) water tanks.
On the water supply pipe to every water heater.

On the fixture supply to each plumbing fixture (with some residential exceptions).
On the water supply to each sillcock.
On the water supply to each appliance or mechanical equipment.

Type M (red stripe): Lightest weight, typically for residential use.
Type L (blue stripe): Used for most systems not subject to damage; common in commercial projects.
Type K (green stripe): Heaviest weight, used below grade and in areas prone to damage; also common in commercial projects.