Licensing Exam Practice Questions And

Water Treatment Operator Class B Licensing Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

(All major subject areas included: Regulations, Safety, Chemistry, Math,

Operations, Disinfection, Distribution, Equipment, Lab & Sampling)

1. The primary purpose of coagulation in water treatment is to:

• Remove dissolved minerals
• Destabilize colloidal particles
• Adjust pH
• Disinfect water

Rationale: Coagulation neutralizes particle charges, allowing them to

clump and settle.

2. Chlorine residual in distribution systems helps to:

• Improve taste only 1 / 3

• Control microbial growth
• Remove hardness
• Add alkalinity

Rationale: A disinfectant residual prevents regrowth and protects public

health.

3. The term alkalinity refers to water’s ability to:

• Cause corrosion
• Neutralize acids
• Support algae growth
• Increase conductivity

Rationale: Alkalinity buffers acids and stabilizes pH.

4. Turbidity is measured in:

• mg/L

B. NTU

C. MGD

• ppm

Rationale: Nephelometric Turbidity Units quantify water cloudiness using

light scattering.

• Which law sets maximum contaminant levels for drinking water?
• Clean Water Act
• Safe Drinking Water Act

C. CERCLA 2 / 3

• OSHA Standards

Rationale: The SDWA regulates drinking water quality and MCLs.

• What is the typical pH range for optimum coagulation?

A. 2–3

B. 4–5

C. 5.5–7.5

D. 8.5–10.5

Rationale: Most coagulants perform best in a slightly acidic to neutral pH

range.

• Which disinfectant provides the longest-lasting residual?
• Ozone
• Chloramines
• UV light
• Calcium hypochlorite

Rationale: Chloramines persist longer in distribution systems.

8. Giardia is best removed by:

• Free chlorine alone
• Filtration
• Fluoridation
• pH adjustment

Rationale: Giardia cysts are resistant to chlorine; filtration is required.

9. The most common cause of high head loss in a filter is:

• Too much chlorine
• / 3