Cross-Connection Control Fundamentals
Backflow prevention purpose, backpressure vs backsiphonage, contamination vs pollution, and why testing matters.
- Define backflow and identify the two causes - backpressure and backsiphonage
- Distinguish between contamination (high hazard) and pollution (low hazard)
- Explain the Venturi effect and water hammer as they relate to water systems
- Describe the purpose and scope of cross-connection control programs
- Identify why annual testing of backflow prevention assemblies is required
Lesson 1
What is Backflow & Why It Matters
The Core Problem
Backflow is the reversal of flow in a water distribution system. Under normal conditions, water flows from the public water supply - through the meter - into buildings and fixtures at positive pressure. Backflow occurs when conditions cause water to flow in the opposite direction, potentially pulling contaminated water back into the potable (drinking) water supply.
A cross-connection is any physical connection between a potable water supply and a non-potable source or system. Cross-connections are the pathways through which backflow can introduce harmful substances into the drinking water supply. Without proper backflow prevention, a single cross-connection can compromise the water safety for an entire building or even an entire water distribution network.
Cross-Connection Control Programs
Every water utility operates a cross-connection control program to protect the public water supply. These programs require:
- Identification of all cross-connections within a service area
- Installation of appropriate backflow prevention assemblies at each cross-connection
- Annual testing of all testable assemblies by certified testers
- Documentation and reporting of all test results to the water utility
The ASSE 5110 certification qualifies you as a backflow prevention assembly tester - the person responsible for performing annual field tests to verify that installed assemblies are functioning correctly and protecting the public water supply.
Why Annual Testing is Required
Backflow prevention assemblies contain internal check valves, springs, and relief valves that are subject to wear, fouling, and degradation. A passing test today does not guarantee protection next year. Annual testing ensures that every assembly in service is verified to be operating within its design parameters. Many jurisdictions also require testing after any repair, after installation, and after relocation.
Exam Tip
The exam frequently asks why testing is required. The answer centers on internal components wearing over time - check valves can foul, springs can weaken, and relief valves can become obstructed.
Scope of ASSE 5110 certification:
The ASSE 5110 tester certification qualifies you to test specific assembly types. Common assemblies within the ASSE 5110 scope include:
- Reduced Pressure Zone (RPZ) assemblies
- Double Check Valve Assemblies (DCVA)
- Pressure Vacuum Breakers (PVB)
- Spill-Resistant Vacuum Breakers (SVB)
- Detector assemblies (DCDA, RPDA)
The certification does NOT qualify you to install or repair assemblies - installation and repair require a licensed plumber, and repair may require additional certification in some jurisdictions. The tester's role is to test and document, then coordinate with the appropriate party for repairs when assemblies fail.
Backflow is the reversal of water flow through a cross-connection, and annual testing by an ASSE 5110 certified tester is required because internal assembly components degrade over time and must be verified each year. The ASSE 5110 certification covers testing only - installation and repair require a licensed plumber or additional credentials.