Cross connections in plumbing systems can pose significant health and safety risks, potentially contaminating your building’s water supply. Identifying and addressing cross connections is essential to maintaining safe, potable water for residential or commercial buildings.

A cross connection occurs when a potable (safe for drinking) water supply is directly or indirectly linked to a non-potable (contaminated) water source. This connection creates a pathway through which contaminants can enter the clean water system, especially during backflow events.

1. Direct Cross Connections:

• Occur when a potable water line is directly connected to a non-potable source, such as an industrial chemical tank or irrigation system.

2. Indirect Cross Connections:

• Occur when the two systems are not physically connected but are linked by a shared medium, such as a garden hose submerged in a pool.

1. Hose Bibbs: Garden hoses connected to outdoor faucets and submerged in pools, buckets, or other non-potable sources.

2. Irrigation Systems: Sprinkler systems that may draw water back into the potable supply during pressure drops.

3. Boiler Systems: Heating systems connected to potable water lines without backflow prevention devices.

4. Utility Sinks: Faucets with hose attachments used near cleaning chemicals or dirty water.

5. Industrial Equipment: Equipment connected to water supplies for cooling or processing that could allow contaminants to backflow.

The primary risk associated with cross connections is backflow, which occurs when water flows in the opposite direction due to:

• Backpressure: Higher pressure in the non-potable system forces contaminated water into the potable supply.

• Backsiphonage: Negative pressure (a vacuum) in the potable supply draws water from the non-potable source.

• Changes in Water Quality: Unusual odors, tastes, or discoloration in the water supply.

• Health Complaints: Illnesses caused by contaminants entering the potable water system.

• Low or Fluctuating Water Pressure: Pressure changes that could trigger backflow events.

• Visible Connections: Hoses or pipes that directly link potable and non-potable systems without safeguards.

1. Inspect for Cross Connections:

• Check all plumbing fixtures, appliances, and external connections for potential cross connections.

• Look for hoses, irrigation systems, or industrial equipment connected to potable water lines.

2. Install Backflow Prevention Devices:

• Atmospheric Vacuum Breakers (AVBs): Prevent backflow by allowing air into the system when negative pressure occurs.

• Reduced Pressure Zone (RPZ) Assemblies: Provide reliable backflow prevention for high-risk applications.

• Double Check Valve Assemblies (DCVAs): Offer protection for low- to medium-risk cross connections.

• Hose Bibb Vacuum Breakers: Attach to outdoor faucets to prevent backflow through hoses.

3. Separate Systems:

• Physically separate potable and non-potable systems wherever possible to eliminate the risk of cross contamination.

4. Regular Maintenance and Testing:

• Schedule annual inspections and testing of backflow prevention devices to ensure they are functioning correctly.

5. Educate Building Occupants:

• Inform tenants, employees, or residents about the risks of cross connections and how to avoid creating them.

6. Comply with Local Codes:

• Adhere to plumbing codes and regulations that mandate backflow prevention measures in building plumbing systems.

• Use Approved Fixtures and Devices: Ensure all plumbing fixtures meet code requirements for backflow prevention.

• Avoid Submersion of Hoses: Keep hoses and other water-carrying equipment above the waterline of sinks, buckets, or pools.

• Install Air Gaps: Provide a physical space between the end of a faucet or pipe and the highest possible water level in a fixture.

• Monitor Plumbing Changes: Ensure renovations or modifications to the plumbing system do not inadvertently create cross connections.

• Protects Public Health: Prevents contaminants like bacteria, chemicals, and waste from entering drinking water.

• Ensures Regulatory Compliance: Avoid fines or penalties for failing to meet local plumbing and health codes.

• Maintains Water Quality: Prevents unpleasant tastes, odors, or discoloration caused by contamination.

• Avoids Costly Repairs: Mitigates damage to plumbing systems and water infrastructure caused by contaminated backflow.

Cross connections are a critical issue in plumbing systems that require prompt attention and preventive measures. By inspecting your system, installing appropriate safeguards, and adhering to best practices, you can ensure the safety and reliability of your building’s water supply. If you suspect a cross connection or need assistance, consult a licensed plumber or backflow prevention specialist.