TEXAS CLASS D WATER LICENSE
2025/ 2026 QUESTIONS WITH
VERIFIED ANSWERS
The process of using chemicals to clot particles together is called coagulation and ? - correct
answer -flocculation
Detention time in sedimentation basins must be at least how many hours? - correct answer -6
Backwashing should expand the filter bed by? - correct answer -30 to 50 %
Chemicals used in disinfection are chloramine, chlorine, chlorine dioxide, and - correct answer -
ozone
Disinfection destroys disease causing microorganisms called? - correct answer -pathogens
Disinfection destroys disease-causing microorganisms called? - correct answer -pathogens
,Disinfection kills pathogens without? which kills all microorganisms. - correct answer -
sterilization
What is sodium hypochlorite? - correct answer -liquid bleach
All water in storage or transported through the distribution system must have a disinfectant? -
correct answer -residual
A disinfectant residual is the amount of ? left over after the demand has been satisfied. - correct
answer -chlorine
Chlorine is used for taste and odor control, oxidation of iron and manganese, oxidation of
hydrogen sulfide and disinfection of? - correct answer -repairs
Calcium hypochlorite comes in granular and powder form and is made by reacting chlorine
with? - correct answer -lime
Disinfection capacity for drinking water must be what percentage greater than the highest
expected dosage? - correct answer -50%
, Dosage is the amount of chemical applied in mg/L or ppm. Demand is the amount of chemical
used up by reducing agents. What is the amount of chemical remaining after reacting with
demand/ - correct answer -residual
DOSAGE = DEMAND + - correct answer -residual
What is the minimum disinfection residual in the distribution system for free chlorine? - correct
answer -0.2 mg/L
What is the minimum disinfection residual in the distribution system for chloramine? - correct
answer -0.5 mg/L
What is the maximum free chlorine or chloramine residual for all community and non-transient,
non community water systems? - correct answer -4 mg/L
DPD (diethyl-p-phenylene-diamine) measures the chlorine residual in water in mg/L. The DPD
and chlorine reaction turns the water a pink to ? color. - correct answer -red
? and water make two acids: hydrocloric (HCL) and hypochlorous (HOCL), the disinfectant. -
correct answer -chlorine
2025/ 2026 QUESTIONS WITH
VERIFIED ANSWERS
The process of using chemicals to clot particles together is called coagulation and ? - correct
answer -flocculation
Detention time in sedimentation basins must be at least how many hours? - correct answer -6
Backwashing should expand the filter bed by? - correct answer -30 to 50 %
Chemicals used in disinfection are chloramine, chlorine, chlorine dioxide, and - correct answer -
ozone
Disinfection destroys disease causing microorganisms called? - correct answer -pathogens
Disinfection destroys disease-causing microorganisms called? - correct answer -pathogens
,Disinfection kills pathogens without? which kills all microorganisms. - correct answer -
sterilization
What is sodium hypochlorite? - correct answer -liquid bleach
All water in storage or transported through the distribution system must have a disinfectant? -
correct answer -residual
A disinfectant residual is the amount of ? left over after the demand has been satisfied. - correct
answer -chlorine
Chlorine is used for taste and odor control, oxidation of iron and manganese, oxidation of
hydrogen sulfide and disinfection of? - correct answer -repairs
Calcium hypochlorite comes in granular and powder form and is made by reacting chlorine
with? - correct answer -lime
Disinfection capacity for drinking water must be what percentage greater than the highest
expected dosage? - correct answer -50%
, Dosage is the amount of chemical applied in mg/L or ppm. Demand is the amount of chemical
used up by reducing agents. What is the amount of chemical remaining after reacting with
demand/ - correct answer -residual
DOSAGE = DEMAND + - correct answer -residual
What is the minimum disinfection residual in the distribution system for free chlorine? - correct
answer -0.2 mg/L
What is the minimum disinfection residual in the distribution system for chloramine? - correct
answer -0.5 mg/L
What is the maximum free chlorine or chloramine residual for all community and non-transient,
non community water systems? - correct answer -4 mg/L
DPD (diethyl-p-phenylene-diamine) measures the chlorine residual in water in mg/L. The DPD
and chlorine reaction turns the water a pink to ? color. - correct answer -red
? and water make two acids: hydrocloric (HCL) and hypochlorous (HOCL), the disinfectant. -
correct answer -chlorine
