Cross-connections exist in nearly every plumbing system. Identifying and evaluating each cross-connection is essential to determine the type of backflow protection required to safeguard the drinking water supply.
Some plumbing fixtures include built-in protection in the form of a physical air gap, which prevents contaminated water from flowing back into the system. However, many cross-connections require additional protection through the installation of an approved mechanical backflow prevention device or assembly.
Common cross-connections found in plumbing and water systems include:
• Wash basins and service sinks
• Hose bibs and exterior faucets
• Irrigation and sprinkler systems
• Auxiliary water supplies
• Swimming pools and hot tubs
• Photo developing equipment
• Solar heating systems
• Boilers
• Fire sprinkler systems
• Water recirculating systems
What is Cross-Connection?
A cross-connection occurs whenever the drinking water system is, or could be, connected to a non-potable source. This can include plumbing fixtures, equipment, or other systems that are not intended for drinking water use.
If a cross-connection is not properly controlled, backflow can occur, allowing pollutants or contaminants to enter the safe drinking water supply.
Where are Cross-Connections Found?
Backflow Preventer Assembly Example
Cross Connection Survey
Example of how a backflow preventer works
Both types of backflow preventors are used to prevent backflow of contaminated water into the potable water system:
Reduced-Pressure Backflow Assembly (RPBA) - used for High-risk scenarios and is normally placed above ground and in a building.
Dual-Check Valve Assembly (DCVA) used for LOW-risk scenarios and is normally berried, only exposing the top. The standard location is near the water meter in a separate box. However, can be located near irrigation controls.
1.Hose bib vacuum breakers are specifically made for portable hoses (ex: garden hose) attached to threaded faucets. Their purpose is to prevent the flow of contaminated water back into the drinking water supply. These devices are not intended for operation under continuous pressure. 2. Backflow prevention assemblies are mechanical devices installed on water services lines (or at plumbing fixtures) to prevent backflow of contaminants into the drinking water supply through cross-connections.
