2026 TEXAS CLASS D WATER LICENSE (COMPLETE) QUESTIONS AND
ANSWERS/GRADE A+ ASSURED!!
Question 1
Which water treatment process involves the incorporation of air into the water through spray
nozzles, steps, cascades, or diffusers to remove tastes, odors, and certain gases?
A) Coagulation
B) Aeration
C) Sedimentation
D) Flocculation
E) Reverse Osmosis
Correct Answer: B) Aeration
Rationale: Aeration is a physical treatment process used to improve water quality by
increasing the contact between air and water. This process is highly effective at stripping
volatile organic compounds (VOCs), reducing dissolved gases like carbon dioxide and
hydrogen sulfide (rotten egg odor), and providing the oxygen necessary to oxidize dissolved
iron and manganese into solid particles for later removal.
Question 2
According to TCEQ regulations, which of the following must be properly managed for all shore
installations, marinas, boats, and houses located on a watershed?
A) Parking facilities
B) Landscaping
C) Sewage disposal
D) Electrical grounding
E) Recreational access
Correct Answer: C) disposal [Sewage Disposal]
Rationale: Protecting the watershed is critical to maintaining source water quality. TCEQ
requires that any structure or vessel on the watershed has an approved and functional
sewage disposal system to prevent the direct discharge of pathogens (like bacteria and
viruses) and nutrients into the water supply, which could lead to health hazards and
excessive algae growth.
Question 3
When water containing dissolved iron and manganese is aerated or chlorinated at the proper pH
level, these minerals are oxidized and converted into what form?
A) Dissolved gases
B) Liquid droplets
C) Solid particles
D) Microorganisms
E) Soluble ions
, 2
Correct Answer: C) particles [Solid Particles]
Rationale: Iron and manganese are typically found in a dissolved (soluble) state in
anaerobic groundwater. Oxidation through aeration or chemical means (like chlorine)
changes their chemical state from soluble to insoluble. Once they become solid particles,
they can be effectively removed through the subsequent steps of sedimentation and
filtration.
Question 4
What are the two primary functions of well casing and cementing in a public water supply well?
A) To increase water temperature and pressure
B) To protect the well from collapse and surface contamination
C) To measure the water level and flow rate
D) To house the vertical turbine pump and motor
E) To allow for easier backwashing of the aquifer
Correct Answer: B) contamination [Protect the well from collapse and surface
contamination]
Rationale: The well casing provides the structural integrity needed to prevent the borehole
from caving in. The cement grout (cementing) fills the space between the casing and the
borehole, creating a sanitary seal that prevents contaminated surface water or shallow,
poor-quality groundwater from migrating down the outside of the casing into the drinking
water aquifer.
Question 5
In the context of iron control, how does the process of "sequestering" differ from other removal
methods?
A) It uses high heat to boil out the iron
B) It physically removes the iron via filtration
C) It prevents iron from combining with oxygen and reddening without removing it
D) It converts iron into a radioactive isotope
E) It uses magnets to pull iron out of the water stream
Correct Answer: C) reddening [Prevents it from combining with oxygen and reddening]
Rationale: Sequestering is a chemical treatment method that uses polyphosphates to
"wrap" or bind dissolved iron. Unlike oxidation and filtration, sequestering does not
remove the iron from the water; instead, it holds it in a transparent, soluble state,
preventing the "red water" stains and complaints that occur when iron is exposed to air or
heat.
Question 6
The quantity of water that a specific geological formation can yield to a well is primarily
dependent on the formation's thickness and which other characteristic?
, 3
A) Color
B) Depth below sea level
C) Permeability
D) Temperature
E) Salinity
Correct Answer: C) permeability
Rationale: Yield is determined by the aquifer's ability to store and transmit water. While
thickness represents the volume of the "reservoir," permeability represents how easily
water can flow through the pores or fractures in the rock. A thick formation with low
permeability will yield less water than a thinner, highly permeable formation.
Question 7
Which of the following equipment types is specifically used to facilitate the aeration of water?
A) Rapid sand filters
B) Centrifugal pumps
C) Cascade aerators and packed air-stripping towers
D) Sludge blanket clarifiers
E) Chlorine gas cylinders
Correct Answer: C) water [Cascade aerators, packed air-stripping towers, and air diffusers
are used to aerate water]
Rationale: Aeration equipment is designed to maximize the surface area of water exposed to
air. Cascade aerators use gravity to drop water over steps; towers use "packing" material
to break water into thin films; and diffusers bubble air up through the water. All three
methods achieve the goal of gas exchange and oxidation.
Question 8
Aeration is an effective pretreatment step for the removal of which two common groundwater
minerals?
A) Calcium and Magnesium
B) Lead and Copper
C) Iron and Manganese
D) Nitrate and Nitrite
E) Sodium and Chloride
Correct Answer: C) iron and manganese
Rationale: Iron and manganese are common in Texas groundwater. Aeration introduces
oxygen, which is the most cost-effective "oxidant" to begin the process of turning these
dissolved minerals into solids. Without this step, these minerals can cause significant
aesthetic issues, such as staining and metallic tastes.
, 4
Question 9
Hydrogen sulfide is a gas commonly found in groundwater that produces a "rotten egg" odor.
How is it typically treated if aeration is insufficient?
A) By adding fluoride
B) Through super-chlorination (oxidation)
C) By decreasing the pH to 4.0
D) By adding more manganese
E) Through the addition of lime
Correct Answer: B) super-chlorination
Rationale: Hydrogen sulfide (H2S) is highly offensive to consumers even at low
concentrations. While aeration can strip much of the gas, super-chlorination provides a
strong chemical oxidation that converts the sulfide into odorless sulfate, effectively
eliminating the "rotten egg" smell.
Question 10
At what concentration does iron in the water supply typically begin to cause red stains on
laundry and plumbing fixtures?
A) 0.01 mg/L
B) 0.1 mg/L
C) 0.3 mg/L
D) 1.0 mg/L
E) 5.0 mg/L
Correct Answer: C) 0.3 mg/L
Rationale: The Secondary Maximum Contaminant Level (SMCL) for iron is 0.3 mg/L.
Concentrations above this level are not usually a health risk but are considered a nuisance
because they cause visible red/orange staining, turbidity, and a distinct metallic taste that
leads to consumer dissatisfaction.
Question 11
Excessive levels of Manganese in a public water system are most likely to cause which aesthetic
problem?
A) Blue water
B) Red stains on clothing
C) Black stains on plumbing fixtures
D) Scale buildup in heaters
E) Increased fluoride levels
Correct Answer: C) black stains
Rationale: Manganese is chemically similar to iron but produces a different aesthetic effect.
ANSWERS/GRADE A+ ASSURED!!
Question 1
Which water treatment process involves the incorporation of air into the water through spray
nozzles, steps, cascades, or diffusers to remove tastes, odors, and certain gases?
A) Coagulation
B) Aeration
C) Sedimentation
D) Flocculation
E) Reverse Osmosis
Correct Answer: B) Aeration
Rationale: Aeration is a physical treatment process used to improve water quality by
increasing the contact between air and water. This process is highly effective at stripping
volatile organic compounds (VOCs), reducing dissolved gases like carbon dioxide and
hydrogen sulfide (rotten egg odor), and providing the oxygen necessary to oxidize dissolved
iron and manganese into solid particles for later removal.
Question 2
According to TCEQ regulations, which of the following must be properly managed for all shore
installations, marinas, boats, and houses located on a watershed?
A) Parking facilities
B) Landscaping
C) Sewage disposal
D) Electrical grounding
E) Recreational access
Correct Answer: C) disposal [Sewage Disposal]
Rationale: Protecting the watershed is critical to maintaining source water quality. TCEQ
requires that any structure or vessel on the watershed has an approved and functional
sewage disposal system to prevent the direct discharge of pathogens (like bacteria and
viruses) and nutrients into the water supply, which could lead to health hazards and
excessive algae growth.
Question 3
When water containing dissolved iron and manganese is aerated or chlorinated at the proper pH
level, these minerals are oxidized and converted into what form?
A) Dissolved gases
B) Liquid droplets
C) Solid particles
D) Microorganisms
E) Soluble ions
, 2
Correct Answer: C) particles [Solid Particles]
Rationale: Iron and manganese are typically found in a dissolved (soluble) state in
anaerobic groundwater. Oxidation through aeration or chemical means (like chlorine)
changes their chemical state from soluble to insoluble. Once they become solid particles,
they can be effectively removed through the subsequent steps of sedimentation and
filtration.
Question 4
What are the two primary functions of well casing and cementing in a public water supply well?
A) To increase water temperature and pressure
B) To protect the well from collapse and surface contamination
C) To measure the water level and flow rate
D) To house the vertical turbine pump and motor
E) To allow for easier backwashing of the aquifer
Correct Answer: B) contamination [Protect the well from collapse and surface
contamination]
Rationale: The well casing provides the structural integrity needed to prevent the borehole
from caving in. The cement grout (cementing) fills the space between the casing and the
borehole, creating a sanitary seal that prevents contaminated surface water or shallow,
poor-quality groundwater from migrating down the outside of the casing into the drinking
water aquifer.
Question 5
In the context of iron control, how does the process of "sequestering" differ from other removal
methods?
A) It uses high heat to boil out the iron
B) It physically removes the iron via filtration
C) It prevents iron from combining with oxygen and reddening without removing it
D) It converts iron into a radioactive isotope
E) It uses magnets to pull iron out of the water stream
Correct Answer: C) reddening [Prevents it from combining with oxygen and reddening]
Rationale: Sequestering is a chemical treatment method that uses polyphosphates to
"wrap" or bind dissolved iron. Unlike oxidation and filtration, sequestering does not
remove the iron from the water; instead, it holds it in a transparent, soluble state,
preventing the "red water" stains and complaints that occur when iron is exposed to air or
heat.
Question 6
The quantity of water that a specific geological formation can yield to a well is primarily
dependent on the formation's thickness and which other characteristic?
, 3
A) Color
B) Depth below sea level
C) Permeability
D) Temperature
E) Salinity
Correct Answer: C) permeability
Rationale: Yield is determined by the aquifer's ability to store and transmit water. While
thickness represents the volume of the "reservoir," permeability represents how easily
water can flow through the pores or fractures in the rock. A thick formation with low
permeability will yield less water than a thinner, highly permeable formation.
Question 7
Which of the following equipment types is specifically used to facilitate the aeration of water?
A) Rapid sand filters
B) Centrifugal pumps
C) Cascade aerators and packed air-stripping towers
D) Sludge blanket clarifiers
E) Chlorine gas cylinders
Correct Answer: C) water [Cascade aerators, packed air-stripping towers, and air diffusers
are used to aerate water]
Rationale: Aeration equipment is designed to maximize the surface area of water exposed to
air. Cascade aerators use gravity to drop water over steps; towers use "packing" material
to break water into thin films; and diffusers bubble air up through the water. All three
methods achieve the goal of gas exchange and oxidation.
Question 8
Aeration is an effective pretreatment step for the removal of which two common groundwater
minerals?
A) Calcium and Magnesium
B) Lead and Copper
C) Iron and Manganese
D) Nitrate and Nitrite
E) Sodium and Chloride
Correct Answer: C) iron and manganese
Rationale: Iron and manganese are common in Texas groundwater. Aeration introduces
oxygen, which is the most cost-effective "oxidant" to begin the process of turning these
dissolved minerals into solids. Without this step, these minerals can cause significant
aesthetic issues, such as staining and metallic tastes.
, 4
Question 9
Hydrogen sulfide is a gas commonly found in groundwater that produces a "rotten egg" odor.
How is it typically treated if aeration is insufficient?
A) By adding fluoride
B) Through super-chlorination (oxidation)
C) By decreasing the pH to 4.0
D) By adding more manganese
E) Through the addition of lime
Correct Answer: B) super-chlorination
Rationale: Hydrogen sulfide (H2S) is highly offensive to consumers even at low
concentrations. While aeration can strip much of the gas, super-chlorination provides a
strong chemical oxidation that converts the sulfide into odorless sulfate, effectively
eliminating the "rotten egg" smell.
Question 10
At what concentration does iron in the water supply typically begin to cause red stains on
laundry and plumbing fixtures?
A) 0.01 mg/L
B) 0.1 mg/L
C) 0.3 mg/L
D) 1.0 mg/L
E) 5.0 mg/L
Correct Answer: C) 0.3 mg/L
Rationale: The Secondary Maximum Contaminant Level (SMCL) for iron is 0.3 mg/L.
Concentrations above this level are not usually a health risk but are considered a nuisance
because they cause visible red/orange staining, turbidity, and a distinct metallic taste that
leads to consumer dissatisfaction.
Question 11
Excessive levels of Manganese in a public water system are most likely to cause which aesthetic
problem?
A) Blue water
B) Red stains on clothing
C) Black stains on plumbing fixtures
D) Scale buildup in heaters
E) Increased fluoride levels
Correct Answer: C) black stains
Rationale: Manganese is chemically similar to iron but produces a different aesthetic effect.
