AWWA Cross Connection Control
Specialist Exam #1
Section 1: Hydraulics & Backflow Principles
1. What causes backsiphonage in a public water supply system?
A. Downstream pressure exceeding the supply line pressure
B. Negative or sub-atmospheric pressure in the supply piping
C. High thermal expansion inside a closed hot water heater
D. Installation of a booster pump downstream of the water meter
Option B is correct because backsiphonage occurs when supply pressure drops below atmospheric
pressure, creating a vacuum that pulls non-potable liquid into the potable system. Option A describes
backpressure, which occurs when downstream pressure exceeds supply pressure.
2. Which hydraulic condition occurs when a downstream source creates a pressure
greater than the potable supply pressure?
A. Backpressure
B. Backsiphonage
C. Atmospheric drawdown
D. Friction head loss
Option A is correct because backpressure happens when downstream pressure rises above the
supply pressure due to pumps, thermal expansion, or elevation heads. Option B is wrong because
backsiphonage requires negative supply pressure.
3. What is the minimum required vertical air gap distance relative to the effective opening
of a supply pipe?
A. Equal to the diameter of the supply pipe
B. One and a half times the diameter of the supply pipe
C. Two times the effective opening diameter of the supply pipe, but never less than 1
inch
D. Three times the effective opening diameter of the supply pipe
Option C is correct because standard plumbing codes mandate an air gap height of at least twice the
supply outlet diameter, with a 1-inch absolute minimum. Option B is a common misconception based
, on fire line clearances.
4. Atmospheric pressure at sea level is approximately equal to how many pounds per
square inch (psi)?
A. 8.34 psi
B. 10.0 psi
C. 14.7 psi
D. 33.9 psi
Option C is correct because standard atmospheric pressure at sea level is 14.7 psi (or 33.9 feet of
water column). Option D represents atmospheric pressure expressed in feet of head rather than psi.
5. One foot of water column exerts how much hydrostatic pressure at its base?
A. 0.334 psi
B. 0.433 psi
C. 0.707 psi
D. 2.31 psi
Option B is correct because dividing 1 psi by 2.31 feet yields 0.433 psi per foot of water column height.
Option D is the inverse, representing the feet of head needed to generate 1 psi.
6. How many feet of head water column are required to produce a pressure of 1 psi?
A. 0.433 feet
B. 1.47 feet
C. 2.31 feet
D. 8.34 feet
Option C is correct because 1 psi equals a 2.31-foot column of fresh water. Option A is the pressure in
psi produced by a single foot of water.
7. What happens to the boiling point of water inside a closed piping system as system
pressure increases?
A. The boiling point increases
B. The boiling point decreases
C. The boiling point remains unchanged at 212°F
D. The water converts immediately to dry steam
Option A is correct because raising ambient pressure suppresses vapor formation, requiring higher
, temperatures for boiling to occur. Option B describes what happens when system pressure drops.
8. A main break in a municipal distribution line typically leads to which potential hazard?
A. Severe backpressure from residential water heaters
B. Backsiphonage caused by sudden negative pressure in the main
C. Thermal expansion across the main service connections
D. Rapid buildup of dissolved oxygen in customer tap lines
Option B is correct because high-velocity water rushing out of a broken pipe creates suction, pulling
stagnant or contaminated water from connected fixtures back into the main.
9. What effect does an increase in fluid velocity have on static pressure within a closed
pipe, according to Bernoulli's principle?
A. Static pressure increases proportionally
B. Static pressure decreases
C. Static pressure drops instantly to zero
D. Static pressure fluctuates randomly without pattern
Option B is correct because Bernoulli's principle dictates that as fluid velocity increases, kinetic energy
rises while static pressure head decreases. Option A describes the opposite relationship.
10. What is the weight of one gallon of fresh water at standard temperature and
pressure?
A. 7.48 lbs
B. 8.34 lbs
C. 10.0 lbs
D. 62.4 lbs
Option B is correct because one U.S. gallon of pure water weighs approximately 8.34 pounds. Option
A is the number of gallons in a cubic foot, and Option D is the weight of one cubic foot of water in
pounds.
11. What is the definition of a cross-connection?
A. Any junction between two municipal water mains
B. Any physical link or arrangement between a potable water system and a non-potable
source
C. An oversized meter bypass piping loop
D. A connection joining PVC pipe to copper tubing
Specialist Exam #1
Section 1: Hydraulics & Backflow Principles
1. What causes backsiphonage in a public water supply system?
A. Downstream pressure exceeding the supply line pressure
B. Negative or sub-atmospheric pressure in the supply piping
C. High thermal expansion inside a closed hot water heater
D. Installation of a booster pump downstream of the water meter
Option B is correct because backsiphonage occurs when supply pressure drops below atmospheric
pressure, creating a vacuum that pulls non-potable liquid into the potable system. Option A describes
backpressure, which occurs when downstream pressure exceeds supply pressure.
2. Which hydraulic condition occurs when a downstream source creates a pressure
greater than the potable supply pressure?
A. Backpressure
B. Backsiphonage
C. Atmospheric drawdown
D. Friction head loss
Option A is correct because backpressure happens when downstream pressure rises above the
supply pressure due to pumps, thermal expansion, or elevation heads. Option B is wrong because
backsiphonage requires negative supply pressure.
3. What is the minimum required vertical air gap distance relative to the effective opening
of a supply pipe?
A. Equal to the diameter of the supply pipe
B. One and a half times the diameter of the supply pipe
C. Two times the effective opening diameter of the supply pipe, but never less than 1
inch
D. Three times the effective opening diameter of the supply pipe
Option C is correct because standard plumbing codes mandate an air gap height of at least twice the
supply outlet diameter, with a 1-inch absolute minimum. Option B is a common misconception based
, on fire line clearances.
4. Atmospheric pressure at sea level is approximately equal to how many pounds per
square inch (psi)?
A. 8.34 psi
B. 10.0 psi
C. 14.7 psi
D. 33.9 psi
Option C is correct because standard atmospheric pressure at sea level is 14.7 psi (or 33.9 feet of
water column). Option D represents atmospheric pressure expressed in feet of head rather than psi.
5. One foot of water column exerts how much hydrostatic pressure at its base?
A. 0.334 psi
B. 0.433 psi
C. 0.707 psi
D. 2.31 psi
Option B is correct because dividing 1 psi by 2.31 feet yields 0.433 psi per foot of water column height.
Option D is the inverse, representing the feet of head needed to generate 1 psi.
6. How many feet of head water column are required to produce a pressure of 1 psi?
A. 0.433 feet
B. 1.47 feet
C. 2.31 feet
D. 8.34 feet
Option C is correct because 1 psi equals a 2.31-foot column of fresh water. Option A is the pressure in
psi produced by a single foot of water.
7. What happens to the boiling point of water inside a closed piping system as system
pressure increases?
A. The boiling point increases
B. The boiling point decreases
C. The boiling point remains unchanged at 212°F
D. The water converts immediately to dry steam
Option A is correct because raising ambient pressure suppresses vapor formation, requiring higher
, temperatures for boiling to occur. Option B describes what happens when system pressure drops.
8. A main break in a municipal distribution line typically leads to which potential hazard?
A. Severe backpressure from residential water heaters
B. Backsiphonage caused by sudden negative pressure in the main
C. Thermal expansion across the main service connections
D. Rapid buildup of dissolved oxygen in customer tap lines
Option B is correct because high-velocity water rushing out of a broken pipe creates suction, pulling
stagnant or contaminated water from connected fixtures back into the main.
9. What effect does an increase in fluid velocity have on static pressure within a closed
pipe, according to Bernoulli's principle?
A. Static pressure increases proportionally
B. Static pressure decreases
C. Static pressure drops instantly to zero
D. Static pressure fluctuates randomly without pattern
Option B is correct because Bernoulli's principle dictates that as fluid velocity increases, kinetic energy
rises while static pressure head decreases. Option A describes the opposite relationship.
10. What is the weight of one gallon of fresh water at standard temperature and
pressure?
A. 7.48 lbs
B. 8.34 lbs
C. 10.0 lbs
D. 62.4 lbs
Option B is correct because one U.S. gallon of pure water weighs approximately 8.34 pounds. Option
A is the number of gallons in a cubic foot, and Option D is the weight of one cubic foot of water in
pounds.
11. What is the definition of a cross-connection?
A. Any junction between two municipal water mains
B. Any physical link or arrangement between a potable water system and a non-potable
source
C. An oversized meter bypass piping loop
D. A connection joining PVC pipe to copper tubing
