10 free, exam-style Water Treatment Operator Grade 1 (WTO1) practice questions with answers and explanations. No signup required. Work through them below, then take the full free WTO1 practice test to study every exam domain.
These 10 free WTO1 questions are organized by exam domain, so you can see how each part of the Water Treatment Operator Grade 1 blueprint is tested. Reveal the answer and explanation under each question.
A plant must apply a chlorine dose of 2.0 mg/L to a flow of 1.0 MGD using sodium hypochlorite that contains 12.5% available chlorine. Approximately how many pounds per day of the sodium hypochlorite are required?
Correct answer: B - 133 lb/day
Disinfection requirements specify a minimum CT of 90 mg/L·min. If the plant maintains a free chlorine residual of 2.0 mg/L through its clearwell, what minimum contact time is needed to meet this requirement?
Correct answer: B - 45 minutes
A rapid sand filter has been in service for an extended run. Headloss is now high and the filtered-water turbidity is steadily climbing. What is the MOST appropriate operator action?
Correct answer: D - Remove the filter from service and initiate a backwash cycle
An operator hears a noise like gravel or marbles passing through a running centrifugal pump, along with vibration and a drop in discharge pressure. These symptoms MOST likely indicate:
Correct answer: A - Cavitation
A facility uses scheduled vibration analysis and oil sampling to detect signs of equipment wear so that repairs can be made just before a failure would occur. This maintenance strategy is BEST described as:
Correct answer: C - Predictive maintenance
An operator must completely shut off and isolate a section of pipe so a pump can be removed for repair. Which valve type is BEST suited for full open/closed isolation service?
Correct answer: D - Gate valve
A distribution-system sample is positive for total coliform and also positive for E. coli. The positive E. coli result is significant primarily because it indicates:
Correct answer: A - The water has been contaminated with fecal material
In a surface water treatment plant, which water quality parameter is MOST commonly monitored as the primary indicator of filter performance?
Correct answer: A - Turbidity
The vertical distance between the static (non-pumping) water level in a well and the lower water level measured while the well is pumping is called the:
Correct answer: C - Drawdown
Before any worker enters a below-grade valve vault classified as a permit-required confined space, the FIRST required action is to:
Correct answer: C - Test the atmosphere inside the space for hazards
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