{modern treatment technologies, regulatory compliance, and certification preparation}
Comprehensive Resource To Help You Ace 2026-2027 Includes
Frequently Tested Questions With ELABORATED 100% Correct
COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!!
Current Update!!
I. CT calculations
II. Pump horsepower
III. Chemical dosage calculations
IV. Detention time
V. Filtration rate
VI. Pipe flow hydraulics Advanced calculations
VII. Membrane system troubleshooting
VIII. Water treatment math
IX. CT calculation problems
X. Pump and hydraulics exam problems
XI. pump curve diagrams
XII. membrane recovery optimization
XIII. distribution pressure balancing
XIV. plant failure troubleshooting scenarios.
XV. Drinking water regulations (SDWA, LT1/LT2, DBP rules)
XVI. MCLs and secondary standards
XVII. Chemical treatment uses
XVIII. Water treatment processes
XIX. Microbiology
XX. Nitrification
XXI. Laboratory testing methods
XXII. Operator troubleshooting concepts
1. CT Calculation
A water plant maintains a chlorine residual of 1.8 mg/L leaving the contact basin. The effective
contact time is 35 minutes.
What is the CT value?
,A. 36
B. 45
C. 63
D. 72
Formula
CT = C × T
C = concentration (mg/L)
T = time (minutes)
Solution
CT = 1.8 × 35
CT = 63
Answer: C
2. Required Contact Time
A system requires a CT of 80 to achieve pathogen inactivation. If the chlorine residual is 2.5
mg/L, what contact time is required?
A. 20 min
B. 28 min
C. 32 min
D. 40 min
Formula
T = CT / C
Solution
T = 80 ÷ 2.5
T = 32 minutes
Answer: C
3. Chlorine Residual Required
A plant must achieve a CT of 100 with a 40-minute contact time.
,What chlorine residual is required?
A. 1.5 mg/L
B. 2.0 mg/L
C. 2.5 mg/L
D. 3.0 mg/L
Formula
C = CT / T
Solution
C = 100 ÷ 40
C = 2.5 mg/L
Answer: C
Section 2 – Pump Horsepower
4. Pump Horsepower Calculation
A pump moves 500 gpm against 120 ft of head.
Pump efficiency = 75%
What is the required horsepower?
A. 15 HP
B. 18 HP
C. 20 HP
D. 25 HP
Formula
HP = (Flow × Head) / (3960 × efficiency)
Efficiency = decimal
Solution
HP = (500 × 120) / (3960 × 0.75)
HP =
HP ≈ 20.2
, Answer: C
5. Pump Power Requirement
A pump moves 800 gpm against 90 ft head with 70% efficiency.
HP = ?
Formula
HP = (Q × H) / (3960 × efficiency)
Solution
HP = (800 × 90) / (3960 × 0.70)
HP =
HP ≈ 26 HP
Section 3 – Chemical Dosage Calculations
6. Chemical Feed Calculation
A plant treats 5 MGD of water with 2 mg/L chlorine.
How many pounds of chlorine per day are required?
A. 60 lbs
B. 83 lbs
C. 90 lbs
D. 120 lbs
Formula
lbs/day = MGD × mg/L × 8.34
Solution
lbs/day = 5 × 2 × 8.34
= 83.4
Answer: B