IA Backflow Prevention & Cross-Connection Control 1 — Questions and Answers
Question 1: What is backflow in an irrigation system?
- Water flowing in the intended direction from supply to outlet
- The reverse flow of water from a non-potable source into the potable water supply (Correct answer)
- Water pressure buildup caused by a closed downstream valve
- The forward flow of water through a check valve assembly
Correct answer: The reverse flow of water from a non-potable source into the potable water supply
Backflow is the unwanted reversal of water flow that can allow contaminants from a non-potable source to enter the clean potable water supply.
Question 2: Which two pressure conditions can cause backflow to occur?
- High pressure and low flow
- Back-siphonage and back-pressure (Correct answer)
- Corrosion and pipe failure
- High flow velocity and low system pressure
Correct answer: Back-siphonage and back-pressure
Backflow is caused by back-siphonage (negative/reduced supply pressure creating a siphon) or back-pressure (downstream pressure exceeding supply pressure).
Question 3: Which of the following represents a high-hazard cross-connection in an irrigation system?
- A garden hose connected to an outdoor residential spigot
- A potable water supply connected to a system with fertilizer injection or recycled water (Correct answer)
- An air gap at an atmospheric tank inlet
- A pressure-reducing valve installed on the main supply line
Correct answer: A potable water supply connected to a system with fertilizer injection or recycled water
Connecting potable water to systems with chemical injectors or recycled water creates a high-hazard cross-connection due to the serious health risk of contamination.
Question 4: What is the definition of a cross-connection?
- A connection between two pipes of different diameters in the same system
- Any physical connection between a potable water supply and a non-potable source (Correct answer)
- A junction where two irrigation lateral lines meet at a tee fitting
- A valve that connects the supply and return lines in a loop system
Correct answer: Any physical connection between a potable water supply and a non-potable source
A cross-connection is any physical link between a potable water system and any source that could introduce contaminants into the drinking water supply.
Question 5: Back-siphonage in an irrigation system is most likely to occur when:
- System pressure is significantly higher than normal operating pressure
- A sudden high demand or break in the supply main creates negative pressure (Correct answer)
- A check valve fails to close properly under forward flow
- The irrigation system operates at peak design flow rate
Correct answer: A sudden high demand or break in the supply main creates negative pressure
Back-siphonage occurs when negative pressure in the supply line draws water backward, commonly caused by high upstream demand, a main break, or firefighting activities.
Question 6: Which organization is the primary authority for backflow prevention standards and tester certification in the United States?
- U.S. Environmental Protection Agency (EPA)
- American Backflow Prevention Association (ABPA)
- USC Foundation for Cross-Connection Control and Hydraulic Research (USC-FCCC) (Correct answer)
- Occupational Safety and Health Administration (OSHA)
Correct answer: USC Foundation for Cross-Connection Control and Hydraulic Research (USC-FCCC)
The USC Foundation for Cross-Connection Control and Hydraulic Research is widely recognized as the primary authority for backflow prevention standards, device approval, and tester certification programs in the U.S.
Question 7: What is the minimum air gap required by most plumbing codes to prevent backflow by siphonage?
- Twice the supply pipe diameter or 1 inch, whichever is greater (Correct answer)
- Equal to the inside diameter of the supply pipe only
- A fixed 6 inches regardless of pipe size
- Half the diameter of the supply pipe, minimum 0.5 inch
Correct answer: Twice the supply pipe diameter or 1 inch, whichever is greater
An air gap must be at least twice the inside diameter of the supply pipe or 1 inch minimum, whichever is greater, to reliably prevent back-siphonage.
IA Backflow Prevention & Cross-Connection Control 1
What is backflow in an irrigation system?