Arkansas AR-WT Water
Treatment Contractor Practice
Exam | Questions, Verified
Answers & Detailed Rationales |
Complete Contractor License
Exam Prep Study Guide |
Updated 2026
1. What is the primary purpose of water treatment?
A. To increase water temperature
B. To reduce water pressure
C. To improve water quality so it is safe and suitable for
its intended use
D. To increase water hardness
Answer: To improve water quality so it is safe and
suitable for its intended use
Rationale: Water treatment removes or controls
contaminants and undesirable characteristics so water
meets applicable quality requirements and is suitable
for consumption or other intended uses.
2. What is the pH of neutral water at approximately
25°C?
A. 0
B. 5
C. 7
D. 14
Answer: 7
,Rationale: A pH of 7 is considered neutral at
approximately 25°C. Values below 7 are acidic and
values above 7 are alkaline.
3. Water with a pH of 5 is:
A. Neutral
B. Acidic
C. Alkaline
D. Saturated
Answer: Acidic
Rationale: The pH scale measures hydrogen-ion activity.
A pH below 7 indicates acidic conditions.
4. What is hardness in water primarily caused by?
A. Sodium and chloride
B. Iron and manganese only
C. Calcium and magnesium
D. Oxygen and nitrogen
Answer: Calcium and magnesium
Rationale: Calcium and magnesium are the principal
minerals responsible for conventional water hardness.
5. Which treatment process is commonly used to remove
hardness?
A. Chlorination
B. Aeration only
C. Ion exchange softening
D. Sedimentation only
Answer: Ion exchange softening
,Rationale: A conventional water softener exchanges
calcium and magnesium ions for sodium or potassium
ions using an ion-exchange resin.
6. What is the purpose of a water softener's brine
solution?
A. To disinfect the plumbing
B. To increase hardness
C. To regenerate the ion-exchange resin
D. To lower water pressure
Answer: To regenerate the ion-exchange resin
Rationale: During regeneration, concentrated sodium
chloride or potassium chloride brine restores the resin's
exchange capacity by replacing accumulated calcium
and magnesium ions.
7. What does turbidity measure?
A. Water temperature
B. Electrical conductivity
C. Cloudiness or lack of clarity in water
D. Chlorine concentration
Answer: Cloudiness or lack of clarity in water
Rationale: Turbidity results from suspended or colloidal
material that scatters light and makes water appear
cloudy.
8. Which unit is commonly used to express turbidity?
A. psi
B. mg/L
C. NTU
D. gpm
, Answer: NTU
Rationale: NTU stands for nephelometric turbidity unit
and is commonly used for reporting turbidity
measurements.
9. What is the primary purpose of filtration?
A. Increase water hardness
B. Remove suspended particles and other filterable
contaminants
C. Add chlorine
D. Increase water temperature
Answer: Remove suspended particles and other
filterable contaminants
Rationale: Filters physically remove suspended solids
and, depending on the media and design, may also
reduce certain other contaminants.
10. Which material is commonly used as granular filter
media?
A. Copper wire
B. Sand
C. PVC pipe
D. Sodium chloride
Answer: Sand
Rationale: Sand is a common filtration medium because
its granular structure provides surfaces and pathways
that capture suspended particles.
11. What is backwashing?
A. Adding salt to a softener
B. Reversing water flow through a filter to clean the
Treatment Contractor Practice
Exam | Questions, Verified
Answers & Detailed Rationales |
Complete Contractor License
Exam Prep Study Guide |
Updated 2026
1. What is the primary purpose of water treatment?
A. To increase water temperature
B. To reduce water pressure
C. To improve water quality so it is safe and suitable for
its intended use
D. To increase water hardness
Answer: To improve water quality so it is safe and
suitable for its intended use
Rationale: Water treatment removes or controls
contaminants and undesirable characteristics so water
meets applicable quality requirements and is suitable
for consumption or other intended uses.
2. What is the pH of neutral water at approximately
25°C?
A. 0
B. 5
C. 7
D. 14
Answer: 7
,Rationale: A pH of 7 is considered neutral at
approximately 25°C. Values below 7 are acidic and
values above 7 are alkaline.
3. Water with a pH of 5 is:
A. Neutral
B. Acidic
C. Alkaline
D. Saturated
Answer: Acidic
Rationale: The pH scale measures hydrogen-ion activity.
A pH below 7 indicates acidic conditions.
4. What is hardness in water primarily caused by?
A. Sodium and chloride
B. Iron and manganese only
C. Calcium and magnesium
D. Oxygen and nitrogen
Answer: Calcium and magnesium
Rationale: Calcium and magnesium are the principal
minerals responsible for conventional water hardness.
5. Which treatment process is commonly used to remove
hardness?
A. Chlorination
B. Aeration only
C. Ion exchange softening
D. Sedimentation only
Answer: Ion exchange softening
,Rationale: A conventional water softener exchanges
calcium and magnesium ions for sodium or potassium
ions using an ion-exchange resin.
6. What is the purpose of a water softener's brine
solution?
A. To disinfect the plumbing
B. To increase hardness
C. To regenerate the ion-exchange resin
D. To lower water pressure
Answer: To regenerate the ion-exchange resin
Rationale: During regeneration, concentrated sodium
chloride or potassium chloride brine restores the resin's
exchange capacity by replacing accumulated calcium
and magnesium ions.
7. What does turbidity measure?
A. Water temperature
B. Electrical conductivity
C. Cloudiness or lack of clarity in water
D. Chlorine concentration
Answer: Cloudiness or lack of clarity in water
Rationale: Turbidity results from suspended or colloidal
material that scatters light and makes water appear
cloudy.
8. Which unit is commonly used to express turbidity?
A. psi
B. mg/L
C. NTU
D. gpm
, Answer: NTU
Rationale: NTU stands for nephelometric turbidity unit
and is commonly used for reporting turbidity
measurements.
9. What is the primary purpose of filtration?
A. Increase water hardness
B. Remove suspended particles and other filterable
contaminants
C. Add chlorine
D. Increase water temperature
Answer: Remove suspended particles and other
filterable contaminants
Rationale: Filters physically remove suspended solids
and, depending on the media and design, may also
reduce certain other contaminants.
10. Which material is commonly used as granular filter
media?
A. Copper wire
B. Sand
C. PVC pipe
D. Sodium chloride
Answer: Sand
Rationale: Sand is a common filtration medium because
its granular structure provides surfaces and pathways
that capture suspended particles.
11. What is backwashing?
A. Adding salt to a softener
B. Reversing water flow through a filter to clean the
