BAT BAT Cross-Connection Control & Risk Assessment 1 — Questions and Answers
Question 1: What is a cross-connection in a potable water system?
- A T-fitting joining two supply mains
- Any actual or potential link between the potable water supply and a source of contamination (Correct answer)
- A valve connecting two different pressure zones
- A bypass line around a backflow prevention assembly
Correct answer: Any actual or potential link between the potable water supply and a source of contamination
A cross-connection is any physical link through which contaminants could enter the potable water supply, whether under current conditions or potential future conditions.
Question 2: Which type of backflow is caused primarily by a loss of pressure in the supply system?
- Back pressure backflow
- Backsiphonage (Correct answer)
- Thermal expansion backflow
- Induced backflow
Correct answer: Backsiphonage
Backsiphonage occurs when negative pressure or a partial vacuum develops in the supply line — such as during a water main break — siphoning contaminants into the system.
Question 3: What is the highest level of cross-connection hazard classification?
- Low hazard (nuisance)
- Moderate hazard
- High hazard (health hazard) (Correct answer)
- Critical hazard (biohazard)
Correct answer: High hazard (health hazard)
A high hazard (health hazard) cross-connection involves substances that could cause illness, injury, or death if they entered the potable water supply.
Question 4: Which backflow prevention assembly provides the highest level of protection and is required for high-hazard cross-connections?
- Double check valve assembly (DCVA)
- Pressure vacuum breaker (PVB)
- Reduced pressure zone assembly (RPZ) (Correct answer)
- Atmospheric vacuum breaker (AVB)
Correct answer: Reduced pressure zone assembly (RPZ)
The RPZ assembly offers the highest mechanical protection because its relief valve vents any backflow to atmosphere, ensuring contaminated water cannot reach the supply even if both checks fail.
Question 5: What is backsiphonage?
- Reverse flow caused by downstream pressure exceeding supply pressure
- Reverse flow caused by negative pressure or vacuum in the supply line (Correct answer)
- Forward flow blocked by a closed check valve
- Contamination entering through a faulty air gap
Correct answer: Reverse flow caused by negative pressure or vacuum in the supply line
Backsiphonage is reverse flow induced by a partial vacuum or negative pressure in the supply piping, essentially sucking water backward from the point of use.
Question 6: What primarily determines the degree of backflow protection required at a cross-connection?
- The pipe diameter at the connection point
- The nature and degree of hazard posed by the connected substance (Correct answer)
- The age of the plumbing system
- The distance from the water meter to the connection
Correct answer: The nature and degree of hazard posed by the connected substance
The hazard level of the substance that could enter the potable supply — whether it would cause illness or only aesthetic degradation — determines which assembly class is required.
BAT BAT Cross-Connection Control & Risk Assessment 1
What is a cross-connection in a potable water system?