Free practice · Water Treatment
Grade 3 Water Treatment Practice Questions
Answer each question, then reveal the correct answer and a full explanation. This is independent study material aligned to commonly tested topics, not official exam questions — exact content varies by state and exam vendor.
Which process is primarily responsible for removing suspended particles by adding a coagulant to neutralize their charge?
You dissolve 5 lbs of a chemical into a total solution weighing 50 lbs. What is the percent strength of the solution?
What is the purpose of the flocculation process that follows coagulation?
Water flows through a 6-inch diameter pipe (cross-sectional area ≈ 0.2 ft²) at a rate of 400 gpm. What is the approximate velocity?
What is the main goal of a source water (watershed) protection program?
A plant treats 2.5 MGD and needs a chlorine dose of 3.0 mg/L. How many pounds of chlorine per day are required?
What is the purpose of maintaining a detectable chlorine residual throughout the distribution system?
What is the primary purpose of the sedimentation (clarification) process?
A sedimentation basin holds 200,000 gallons and receives a flow of 800,000 gallons per day. What is the detention time?
What is the key difference between conventional filtration and direct filtration?
A clearwell maintains a chlorine residual of 1.2 mg/L with a contact time of 30 minutes. What is the CT value?
Which water condition is most likely to increase corrosivity toward lead and copper plumbing?
A water sample requires a chlorine dose of 2.5 mg/L to achieve a free chlorine residual of 0.8 mg/L. What is the chlorine demand?
Trihalomethanes (THMs), a regulated class of disinfection byproducts, primarily form when:
A filter is 15 ft by 10 ft and requires a backwash rate of 15 gpm/ft². What total backwash flow rate is needed?
Want the full topic breakdown for this exam? See the Grade 3 Water Treatment exam guide, or start from the Water Treatment overview.