CLASS A WATER OPERATOR TEST PAPER 2025/2026
QUESTIONS WITH SOLUTIONS RATED A+
✔✔50% above working pressure or 150 psi. Whichever is greater. Must hold for 4 hrs. -
✔✔What pressure should lines be tested at and for how long?
✔✔Thicker - ✔✔The larger the pipe schedule number the ____the pipe wall.
✔✔Tuberculation - ✔✔Small mounds of corrosion in iron pipe.
✔✔Corrosion control - ✔✔Cathodic/Ionic protection is used for
✔✔Lime or phosphates/after filter - ✔✔What can be added to water to help with
corrosion control? When?
✔✔Magnesium or Zinc - ✔✔Anodes for corrosion control are made of what?
✔✔Aeration, activated carbon, potassium permanganate, chlorine dioxide. - ✔✔Ways to
help with test and odor:
✔✔Calcium and Magnesium ions - ✔✔What causes hardness in water?
✔✔Lime softening/Zeolite - ✔✔What can be done to soften water when it's hard?
✔✔0.3 NTU's or lower 95% of the time. - ✔✔Acceptable turbidity is:
✔✔90 days with Formazine - ✔✔Turbidity meters should be calibrated how often? With
what?
✔✔24 hrs by phone. - ✔✔Turbidity and Disinfection violations should be reported to
regional engineer within ____
✔✔Coagulation, flocculation, sedimentation, filtration. - ✔✔Process to help reduce
turbidity:
✔✔Apparent: before, True: after - ✔✔Before or after filtration: Apparent color, True color
✔✔Disinfection: kills microbes to safe level.
Sterilization: kills everything. - ✔✔Difference in disinfection and sterilization.
✔✔Chlorination - ✔✔Most widely used disinfectant
✔✔Monochloramines - ✔✔Chlorine plus ammonia form ____
, ✔✔Bleach - ✔✔Sodium hypochlorite is
✔✔Demand ends and free residual starts - ✔✔Breakpoint in chlorination is where
✔✔2.5 times - ✔✔Chlorine is how much heavier than air?
✔✔1 to 450 - ✔✔Chlorine liquid to gas ratio is
✔✔40 lbs - ✔✔Maximum draw from a 150 per day is
✔✔10 day - ✔✔A water system must have at least a ____ day supply of chlorine.
✔✔DPD (N, N-diethyl-p-phenylene-diamine) - ✔✔Reagent used to test chlorine residual
✔✔400 lbs. / 9,600 lbs/day - ✔✔Max Cl2 pulled from a 1 ton at 70 degrees is ____.
Using an evaporator is ____
✔✔158-165 F - ✔✔Fusible plugs melt at what temp?
✔✔1, 6 to 8 - ✔✔150 Cl2 has how many fusible plugs? One ton has how many?
✔✔"A" Red: 150
"B" Yellow: one ton
"C" Green: rail tank - ✔✔Cl2 repair kits are
✔✔Trihalomethanes (THMs) - ✔✔Byproduct from Cl2 that can be prevented with
ammonia is:
✔✔Disinfection by-products - ✔✔DBP's are:
✔✔Aeration, Activated carbon filters (Adsorption) or oxidation. - ✔✔Remove
Trihalomethanes with:
✔✔The logarithm (base 10) of the reciprocal of the hydrogen ion activity. - ✔✔Definition
of pH is:
✔✔Raised - ✔✔When lime softening, pH must be
✔✔6.5-8.5 - ✔✔SMCL for pH is:
✔✔Lower - ✔✔Chlorine works better in lower or higher pH?
QUESTIONS WITH SOLUTIONS RATED A+
✔✔50% above working pressure or 150 psi. Whichever is greater. Must hold for 4 hrs. -
✔✔What pressure should lines be tested at and for how long?
✔✔Thicker - ✔✔The larger the pipe schedule number the ____the pipe wall.
✔✔Tuberculation - ✔✔Small mounds of corrosion in iron pipe.
✔✔Corrosion control - ✔✔Cathodic/Ionic protection is used for
✔✔Lime or phosphates/after filter - ✔✔What can be added to water to help with
corrosion control? When?
✔✔Magnesium or Zinc - ✔✔Anodes for corrosion control are made of what?
✔✔Aeration, activated carbon, potassium permanganate, chlorine dioxide. - ✔✔Ways to
help with test and odor:
✔✔Calcium and Magnesium ions - ✔✔What causes hardness in water?
✔✔Lime softening/Zeolite - ✔✔What can be done to soften water when it's hard?
✔✔0.3 NTU's or lower 95% of the time. - ✔✔Acceptable turbidity is:
✔✔90 days with Formazine - ✔✔Turbidity meters should be calibrated how often? With
what?
✔✔24 hrs by phone. - ✔✔Turbidity and Disinfection violations should be reported to
regional engineer within ____
✔✔Coagulation, flocculation, sedimentation, filtration. - ✔✔Process to help reduce
turbidity:
✔✔Apparent: before, True: after - ✔✔Before or after filtration: Apparent color, True color
✔✔Disinfection: kills microbes to safe level.
Sterilization: kills everything. - ✔✔Difference in disinfection and sterilization.
✔✔Chlorination - ✔✔Most widely used disinfectant
✔✔Monochloramines - ✔✔Chlorine plus ammonia form ____
, ✔✔Bleach - ✔✔Sodium hypochlorite is
✔✔Demand ends and free residual starts - ✔✔Breakpoint in chlorination is where
✔✔2.5 times - ✔✔Chlorine is how much heavier than air?
✔✔1 to 450 - ✔✔Chlorine liquid to gas ratio is
✔✔40 lbs - ✔✔Maximum draw from a 150 per day is
✔✔10 day - ✔✔A water system must have at least a ____ day supply of chlorine.
✔✔DPD (N, N-diethyl-p-phenylene-diamine) - ✔✔Reagent used to test chlorine residual
✔✔400 lbs. / 9,600 lbs/day - ✔✔Max Cl2 pulled from a 1 ton at 70 degrees is ____.
Using an evaporator is ____
✔✔158-165 F - ✔✔Fusible plugs melt at what temp?
✔✔1, 6 to 8 - ✔✔150 Cl2 has how many fusible plugs? One ton has how many?
✔✔"A" Red: 150
"B" Yellow: one ton
"C" Green: rail tank - ✔✔Cl2 repair kits are
✔✔Trihalomethanes (THMs) - ✔✔Byproduct from Cl2 that can be prevented with
ammonia is:
✔✔Disinfection by-products - ✔✔DBP's are:
✔✔Aeration, Activated carbon filters (Adsorption) or oxidation. - ✔✔Remove
Trihalomethanes with:
✔✔The logarithm (base 10) of the reciprocal of the hydrogen ion activity. - ✔✔Definition
of pH is:
✔✔Raised - ✔✔When lime softening, pH must be
✔✔6.5-8.5 - ✔✔SMCL for pH is:
✔✔Lower - ✔✔Chlorine works better in lower or higher pH?
