ARIZONA WATER TREATMENT OPERATOR EXAM QUESTIONS
AND ANSWERS - 100% VERIFIED - LATEST 2026/2027
GUARANTEED PASS
1. What is the formula for calculating flow rate in an open channel?
ANSWER
Q=V×A
(Flow = Velocity
×
Area)
2. Convert 4 feet into inches. ANSWER 48 inches
3. Convert 250 gallons to cubic feet. ANSWER
250÷7.48=33.4
cubic feet
4. Calculate the detention time in a tank that holds 50,000 gallons with a
flow of 200 gpm. ANSWER
50,000÷200=250
minutes
5. What is the area of a circular tank with a diameter of 40 feet? ANSWER
Area
=πr2=3.14×202=1,256
square feet
6. Calculate the volume of a cylindrical tank 20 feet in diameter and 10
feet deep (in gallons). ANSWER Volume
=3.14×102×10=3,140
cubic feet.
,3,140×7.48=23,487
gallons.
7. Convert 2.5 MGD to gpm. ANSWER
(2.5×1,000,000)÷1440=1,736
gpm
8. What is the weir overflow rate if the flow is 2 MGD and the weir length
is 100 ft? ANSWER
(2,000,000÷1440)=1,389
gpm.
1,389÷100=13.9
gpm/ft.
9. Calculate the filtration rate in gpm/ft² if the flow is 500 gpm and the
filter surface area is 50 ft². ANSWER
500÷50=10
gpm/ft²
10. If a chemical feed pump delivers 5 mL/min and the solution strength
is 10%, what is the actual feed rate of pure chemical? ANSWER 0.5
mL/min
11. How many pounds of chemical are needed to make a 5% solution in a
500-gallon tank? ANSWER
500 gal×8.34 lbs/gal×0.05=208.5
lbs
12. Convert 45 psi to feet of head. ANSWER
45×2.31=103.95
feet
13. Convert 100 feet of head to psi. ANSWER
100÷2.31=43.3
psi
, 14. What is the velocity of water in a 12-inch pipe carrying 2,000 gpm?
ANSWER Area
=0.785×12=0.785
ft².
Q (cfs)=2000÷448.8=4.46
cfs.
V=Q÷A=4.46÷0.785=5.68
ft/s.
15. Calculate the chlorine demand if the chlorine dose is 3.0 mg/L and the
residual is 0.5 mg/L. ANSWER
3.0−0.5=2.5
mg/L
16. If a plant treats 5 MGD and uses 100 lbs of chlorine per day, what is
the dose in mg/L? ANSWER Dose
=(100×2)÷5=40
lbs/day per MGD. Since 1 mg/L = 8.34 lbs/MG, the dose is approx 4.8
mg/L (or simply
100 lbs/day÷(5 MGD×8.34)=2.4
mg/L). Note: 100 lbs/day / 41.7 = 2.4 mg/L.
17. Calculate the miles per gallon for a pump if it pumps 1,000,000 gallons
using $500 of electricity at $0.10 per kWh. (This is a logic trap, skipping
to standard pump eff). 17. A pump delivers 500 gpm against a head of
100 psi. What is the water horsepower (whp)? ANSWER
Q=500 gpm,H=100×2.31=231
ft.
whp=(Q×H)÷3960=(500×231)÷3960=29.17
hp.
18. If a tank is 30 ft wide, 40 ft long, and 15 ft deep, what is the volume in
gallons? ANSWER
AND ANSWERS - 100% VERIFIED - LATEST 2026/2027
GUARANTEED PASS
1. What is the formula for calculating flow rate in an open channel?
ANSWER
Q=V×A
(Flow = Velocity
×
Area)
2. Convert 4 feet into inches. ANSWER 48 inches
3. Convert 250 gallons to cubic feet. ANSWER
250÷7.48=33.4
cubic feet
4. Calculate the detention time in a tank that holds 50,000 gallons with a
flow of 200 gpm. ANSWER
50,000÷200=250
minutes
5. What is the area of a circular tank with a diameter of 40 feet? ANSWER
Area
=πr2=3.14×202=1,256
square feet
6. Calculate the volume of a cylindrical tank 20 feet in diameter and 10
feet deep (in gallons). ANSWER Volume
=3.14×102×10=3,140
cubic feet.
,3,140×7.48=23,487
gallons.
7. Convert 2.5 MGD to gpm. ANSWER
(2.5×1,000,000)÷1440=1,736
gpm
8. What is the weir overflow rate if the flow is 2 MGD and the weir length
is 100 ft? ANSWER
(2,000,000÷1440)=1,389
gpm.
1,389÷100=13.9
gpm/ft.
9. Calculate the filtration rate in gpm/ft² if the flow is 500 gpm and the
filter surface area is 50 ft². ANSWER
500÷50=10
gpm/ft²
10. If a chemical feed pump delivers 5 mL/min and the solution strength
is 10%, what is the actual feed rate of pure chemical? ANSWER 0.5
mL/min
11. How many pounds of chemical are needed to make a 5% solution in a
500-gallon tank? ANSWER
500 gal×8.34 lbs/gal×0.05=208.5
lbs
12. Convert 45 psi to feet of head. ANSWER
45×2.31=103.95
feet
13. Convert 100 feet of head to psi. ANSWER
100÷2.31=43.3
psi
, 14. What is the velocity of water in a 12-inch pipe carrying 2,000 gpm?
ANSWER Area
=0.785×12=0.785
ft².
Q (cfs)=2000÷448.8=4.46
cfs.
V=Q÷A=4.46÷0.785=5.68
ft/s.
15. Calculate the chlorine demand if the chlorine dose is 3.0 mg/L and the
residual is 0.5 mg/L. ANSWER
3.0−0.5=2.5
mg/L
16. If a plant treats 5 MGD and uses 100 lbs of chlorine per day, what is
the dose in mg/L? ANSWER Dose
=(100×2)÷5=40
lbs/day per MGD. Since 1 mg/L = 8.34 lbs/MG, the dose is approx 4.8
mg/L (or simply
100 lbs/day÷(5 MGD×8.34)=2.4
mg/L). Note: 100 lbs/day / 41.7 = 2.4 mg/L.
17. Calculate the miles per gallon for a pump if it pumps 1,000,000 gallons
using $500 of electricity at $0.10 per kWh. (This is a logic trap, skipping
to standard pump eff). 17. A pump delivers 500 gpm against a head of
100 psi. What is the water horsepower (whp)? ANSWER
Q=500 gpm,H=100×2.31=231
ft.
whp=(Q×H)÷3960=(500×231)÷3960=29.17
hp.
18. If a tank is 30 ft wide, 40 ft long, and 15 ft deep, what is the volume in
gallons? ANSWER
