WTO Study Guide 2026
Everything you need to pass the WTO exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 WTO Exam Format at a Glance
📚 WTO Topics to Study (63)
✍️ Sample WTO Questions & Answers
1. What type of chlorine residual is measured after the breakpoint has been reached?
After breakpoint, all combined chlorine (chloramines) has been destroyed; any additional chlorine added exists as free chlorine residual.
2. What is the action level for copper under the Lead and Copper Rule that triggers additional treatment requirements?
The action level for copper is 1.3 mg/L; if exceeded at the 90th percentile of tap samples, the system must take corrective actions including public education.
3. What does a Secchi disk measurement indicate about source water quality in a reservoir?
The Secchi disk depth — how deep the disk remains visible — is a simple field method to estimate water transparency, which correlates with turbidity and algal growth.
4. A gas chlorinator feeds at 8 lbs/day and plant flow is 2 MGD. What is the applied chlorine dose in mg/L?
Dose (mg/L) = Feed rate ÷ (Flow × 8.34): 8 lbs/day ÷ (2 MGD × 8.34) = 8 ÷ 16.68 = 0.48 mg/L.
5. Which of the following is a key safety practice in water treatment plants?
Using personal protective equipment (PPE) is a fundamental safety practice in water treatment plants. Operators routinely handle hazardous chemicals, work with machinery, and may be exposed to pathogens. PPE such as gloves, safety glasses, respirators, and hard hats provides essential protection against chemical splashes, airborne contaminants, physical impacts, and other workplace hazards, minimizing the risk of injury or illness.
6. Which watershed land use practice most significantly increases the risk of nitrate contamination in a groundwater source?
Nitrogen-based fertilizers applied to cropland leach into groundwater as nitrate, especially in sandy or permeable soils.