• Definition: A cross-connection refers to any actual or potential connection between a drinking water system and a source of pollution or contamination.
• Purpose: Cross-connections need to be identified and eliminated or controlled to prevent the backflow of contaminated water into the clean water supply.

• Definition: A backflow preventer is a device or assembly designed to prevent backflow from occurring.
• Types: There are different types of backflow preventers available, and their selection depends on the specific application and level of protection required.
• Testing Requirements: Some types of backflow preventers, known as testable devices, require periodic testing by trained and qualified professionals to ensure proper functioning. Other types, such as air gaps, may require visual inspections.

• Definition: A backflow preventer is a device or assembly designed to prevent backflow from occurring.
• Types: There are different types of backflow preventers available, and their selection depends on the specific application and level of protection required.
• Testing Requirements: Some types of backflow preventers, known as testable devices, require periodic testing by trained and qualified professionals to ensure proper functioning. Other types, such as air gaps, may require visual inspections.

• Functioning Verification: Mechanical backflow preventers have internal components that can be subject to fouling, wear, or fatigue over time. Periodic testing ensures that these devices are functioning as intended.
• Bypass Prevention: Backflow preventers can be bypassed or tampered with, compromising their effectiveness. Regular testing helps identify any potential issues or unauthorized modifications.
• Qualified Testing: Testing of backflow preventers should be conducted by individuals who have received proper training and certification to ensure accurate and reliable results.

• Water Contamination Prevention: Backflow into a public water system can introduce pollutants or contaminants, posing health risks to consumers.
• Hazards Classification: Backflow hazards can be categorized as severe, moderate, or minor based on their potential impact on water quality and health.
• Responsibility of Water Purveyors: Water suppliers have the responsibility to provide safe, potable water under all circumstances and must take precautions to protect public water systems against backflow.
• Backflow Prevention Measures: Water purveyors should implement proper backflow prevention devices and strategies, such as premise isolation and zone protection, to control cross-connections and protect public water systems.

There are two types of backflow prevention devices that are commonly used to prevent backflow incidents. The first type is a Double Check Valve Assembly (DCVA), which is typically required for facilities that are classified as “moderate hazard.” DCVAs are designed to provide protection against low to moderate risk of backflow incidents.

The second type is a Reduced Pressure Principle Assembly (RP), which is required for facilities that are classified as “severe hazard.” RPs offer more comprehensive protection against high-risk backflow incidents.

• Back Pressure: Occurs when private system pressure exceeds the city’s due to factors like pumps or temperature changes.
• Back Siphonage: Happens when city pressure drops below private systems, often during firefighting or water main breaks.