REHS EXAM Question and Answer 2026
| Latest Questions with Complete
Explanations | Grade A+
• Water table. CORRECT ANSWER: top of saturated zone
• Vadose zone. CORRECT ANSWER: part of unsaturated zone
• Flowing artesian well. CORRECT ANSWER: pressure causes water to rise above
ground level
• Aquaclude. CORRECT ANSWER: Confining layer, rock or clay
• Confined aquifer. CORRECT ANSWER: groundwater below layer of solid rock or
clay
• Aquitard. CORRECT ANSWER: retards flow of water
• 2 biggest water users. CORRECT ANSWER: 1. Therm-electric power
2. Irrigation
• Public water system. CORRECT ANSWER: At least 25 people, 15+ service
connections
• Community water system. CORRECT ANSWER: 25 people, 15+ connections,
year-round
• Non-transient, non-community. CORRECT ANSWER: 25 people, 6+ months
• Transient, non-community. CORRECT ANSWER: 25 people, 60 days+
• Treatment plant standards. CORRECT ANSWER: 1. well equipped lab
2. qualified chemist
3. EPA certified operator
, • Early treatment techniques. CORRECT ANSWER: -chlorination
-slow sand filtration
-rapid sand filtration
• Modern treatment techniques. CORRECT ANSWER: coagulation & flocculation
• Water filtration process. CORRECT ANSWER: 1. Pre-treatment
2. Coagulation
3. Flocculation
4. Sedimentation
5.Filtration
6.Post-treatment sanitizing
• Field tests for residual chlorine. CORRECT ANSWER: -DPD: preferred,
colorimetric
-SNORT: Stabilized Neutral Orthotolidine
-FACTS: Free Available Chlorine Test
• Surface water treatment rule. CORRECT ANSWER: Applies to systems that use
surface water
• Fecal coliform bacteria. CORRECT ANSWER: Found in gut & feces of warm-
blooded animals
• Lead and Copper. CORRECT ANSWER: monitor at customer taps
• Turbidity. CORRECT ANSWER: caused by suspended solids
NOT to exceed 0.5 NTU in 95% of samples
NOT to exceed 1.0 NTU
• Waterborne viruses. CORRECT ANSWER: Enterovirus
Rotavirus
Norwalk virus
Hep A
• Norwalk virus. CORRECT ANSWER: Norwalk like virus
Reservoir: humans
| Latest Questions with Complete
Explanations | Grade A+
• Water table. CORRECT ANSWER: top of saturated zone
• Vadose zone. CORRECT ANSWER: part of unsaturated zone
• Flowing artesian well. CORRECT ANSWER: pressure causes water to rise above
ground level
• Aquaclude. CORRECT ANSWER: Confining layer, rock or clay
• Confined aquifer. CORRECT ANSWER: groundwater below layer of solid rock or
clay
• Aquitard. CORRECT ANSWER: retards flow of water
• 2 biggest water users. CORRECT ANSWER: 1. Therm-electric power
2. Irrigation
• Public water system. CORRECT ANSWER: At least 25 people, 15+ service
connections
• Community water system. CORRECT ANSWER: 25 people, 15+ connections,
year-round
• Non-transient, non-community. CORRECT ANSWER: 25 people, 6+ months
• Transient, non-community. CORRECT ANSWER: 25 people, 60 days+
• Treatment plant standards. CORRECT ANSWER: 1. well equipped lab
2. qualified chemist
3. EPA certified operator
, • Early treatment techniques. CORRECT ANSWER: -chlorination
-slow sand filtration
-rapid sand filtration
• Modern treatment techniques. CORRECT ANSWER: coagulation & flocculation
• Water filtration process. CORRECT ANSWER: 1. Pre-treatment
2. Coagulation
3. Flocculation
4. Sedimentation
5.Filtration
6.Post-treatment sanitizing
• Field tests for residual chlorine. CORRECT ANSWER: -DPD: preferred,
colorimetric
-SNORT: Stabilized Neutral Orthotolidine
-FACTS: Free Available Chlorine Test
• Surface water treatment rule. CORRECT ANSWER: Applies to systems that use
surface water
• Fecal coliform bacteria. CORRECT ANSWER: Found in gut & feces of warm-
blooded animals
• Lead and Copper. CORRECT ANSWER: monitor at customer taps
• Turbidity. CORRECT ANSWER: caused by suspended solids
NOT to exceed 0.5 NTU in 95% of samples
NOT to exceed 1.0 NTU
• Waterborne viruses. CORRECT ANSWER: Enterovirus
Rotavirus
Norwalk virus
Hep A
• Norwalk virus. CORRECT ANSWER: Norwalk like virus
Reservoir: humans
