Water Supply - Cross-Contamination Control

It is fundamental to keep the potable water in the water supply systems uncontaminated. A cross-contamination between potentially contaminated water and public water supply systems can occur when the pressure in the supply system is interrupted by a water main break, power failure or some other disruptions in the water service.

Prevention Methods

Cross-contamination can be prevented by:

• Vacuum Breakers in pipe lines or hoses
• Air Gaps between fixtures and potentially contaminated water surfaces
• Check Valves to prevent backflow

Air Gap Requirements

The air gap should be larger for larger fixtures and closed surfaces than for smaller fixtures and open surfaces:

• 1/2" fixture: Minimum 1" for open surface, 1.5" for closed surface
• 1" fixture: Minimum 2" for open surface, 3" for closed surface