Page 1 of 162
NGWA Water Systems General Certification Exam
ACTUAL QUESTIONS AND ANSWERS LATEST
UPDATE THIS YEAR
NGWA Water Systems General Certification Exam
Point-Form Exam Coverage (Based on NGWA Core Competencies & 2024 Exam Outline)
Based on the National Ground Water Association (NGWA) Water Systems General Certification exam
blueprint, the exam covers the following major domains and industry standards, including NGWA's
"Certified Contractors Code of Excellence" .
Regulatory & Safety Foundation (10-15%)
• Safe Drinking Water Act (SDWA)
• Ground Water Rule (GWR) – requires sanitary completion and source water monitoring
• National Primary Drinking Water Regulations (NPDWR) – enforceable standards
• National Secondary Drinking Water Regulations – non-enforceable aesthetic guidelines
• OSHA 1926 Subpart P – trenching and excavation safety
• Lock-out/Tag-out (LOTO) – required when servicing pumps
• Confined space entry – atmospheric testing requirements
Well Construction & Development (20-25%)
• NGWA "Contractors Code of Excellence": install casing to at least 18 ft depth, surface seal,
sanitary well cap, pitless adapter
• Grouting requirements: Bentonite (minimum 20% solids for well seal)
• Surface seal: Minimum 18 ft depth; annular space grouted at least 10 ft for confined aquifers
• Sanitary well cap – prevents surface water entry
• Pitless adapter – eliminates frost heave, allows below-frost-line connection while maintaining
sanitary seal
• Annular space grouting to prevent vertical migration of contaminants
• Gravel pack design for sand control (filter pack for naturally unstable formations)
• Well development methods: surging (most effective for fine sand), air lift, overpumping, bailing
• Screen types: continuous slot (most open area), slotted casing, wire wrap, louvered
Pump Systems & Hydraulics (20-25%)
• Pump types: Submersible pump (most common for water wells), line shaft turbine, jet pump
(shallow and deep)
• Pump affinity laws: Flow (Q) varies directly with speed (N); Head (H) varies with N²; Power (P)
varies with N³
• Total Dynamic Head (TDH) = Static Lift + Friction Loss + Pressure Head (delivery pressure, if any)
• NPSH (Net Positive Suction Head) – critical for centrifugal pumps; not applicable to submersibles
• Motor sizing: 1 HP = 746 watts; service factor = ability to run above rated HP intermittently
• Cable sizing: voltage drop limits (max 3-5% for motors)
• Check valves – prevent backflow; required at pump discharge
• Torque arrestors – prevent twisting in the well
• Flow meters – required for compliance monitoring
Water Quality & Treatment (15-20%)
• Common contaminants: Iron, manganese, hardness, hydrogen sulfide (rotten egg odor)
• Treatment methods: Iron filtration (oxidation + filtration); Water softeners (ion exchange)
, Page 2 of 162
• Disinfection: Chlorination (shock chlorination for new wells, maintenance, after repairs); UV
disinfection (requires clear water)
• Reverse osmosis (RO) – removes TDS, nitrates, arsenic; produces wastewater
• Distillation – energy-intensive, removes most contaminants
• Corrosive water – addressed by pH adjustment or neutralizing filter (calcite)
• Coliform bacteria – causes gastrointestinal illness; requires disinfection
• Manganese – brown/black staining; lower secondary MCL than iron
• Aeration – removes hydrogen sulfide, radon, volatile organics, iron
• Bacterial iron – iron bacteria; requires disinfection and physical removal
• Filtration – turbidity removal
System Maintenance & Troubleshooting (15-20%)
• Pressure switch settings: Common 20/40, 30/50, 40/60 psi (typical differential of 20 psi)
• Pressure tank – provides drawdown volume; prevents short cycling
• Low yield troubleshooting: Pump cycles on/off rapidly (short cycling) → check pressure tank air
charge, bladder, or possible low yield
• Pump not delivering water: Check power, pressure switch, check valve, pump protection devices
(overload, low water cut-off)
• Air-locked pumps – common after repair, need to bleed air from discharge
• Galvanic corrosion – occurs when dissimilar metals are connected (use dielectric unions)
• Sand in water – well screen failure, gravel pack collapse, or overpumping
• Water level measurement – using electric sounder or air line
• Specific capacity = yield (gpm) / drawdown (ft) – declines with well age
Business & Professional Practice (5-10%)
• Customer service: written estimates, contracts, warranties
• NGWA Code of Excellence – ethical standards, transparency, responsible groundwater
stewardship
• Permit requirements – vary by state/local jurisdiction; contractor responsible for compliance
Question 1
A well driller is installing a new residential water well in an area with a shallow water table. According to
the NGWA Code of Excellence, what is the minimum depth to which casing must be installed to provide
a sanitary seal?
A) 10 feet
, Page 3 of 162
B) 18 feet
C) 25 feet
D) 50 feet
Answer: B
The NGWA Code of Excellence requires casing to be installed to a minimum depth of 18 feet, or through
unconsolidated material to competent bedrock, to prevent surface water contamination.
Question 2
During a pump service call, the technician finds that the submersible pump runs continuously but
delivers very little water. The pressure gauge shows pressure fluctuating between 20 and 30 psi. What is
the most likely cause?
A) The pressure tank is waterlogged (no air cushion)
B) The check valve is stuck closed
C) The pump motor is overheating
D) The pressure switch is set too high
Answer: A
, Page 4 of 162
A waterlogged pressure tank (bladder failure or lost air charge) causes rapid pressure changes and
short-cycling; the pump runs frequently without holding pressure.
Question 3
A well drilled into a confined aquifer must have the annular space sealed to prevent what?
A) Loss of aquifer pressure only
B) Vertical migration of contaminants from overlying formations into the confined aquifer
C) Corrosion of the casing
D) Entry of sand into the well
Answer: B
Annular space grouting (minimum 10 ft in confined aquifers) seals off the annulus to prevent water and
contaminants from moving vertically between aquifers.
Question 4
An irrigation well produces water that contains hydrogen sulfide (rotten egg odor). Which treatment
method is most effective for removing hydrogen sulfide from well water?
A) Water softener (ion exchange)
NGWA Water Systems General Certification Exam
ACTUAL QUESTIONS AND ANSWERS LATEST
UPDATE THIS YEAR
NGWA Water Systems General Certification Exam
Point-Form Exam Coverage (Based on NGWA Core Competencies & 2024 Exam Outline)
Based on the National Ground Water Association (NGWA) Water Systems General Certification exam
blueprint, the exam covers the following major domains and industry standards, including NGWA's
"Certified Contractors Code of Excellence" .
Regulatory & Safety Foundation (10-15%)
• Safe Drinking Water Act (SDWA)
• Ground Water Rule (GWR) – requires sanitary completion and source water monitoring
• National Primary Drinking Water Regulations (NPDWR) – enforceable standards
• National Secondary Drinking Water Regulations – non-enforceable aesthetic guidelines
• OSHA 1926 Subpart P – trenching and excavation safety
• Lock-out/Tag-out (LOTO) – required when servicing pumps
• Confined space entry – atmospheric testing requirements
Well Construction & Development (20-25%)
• NGWA "Contractors Code of Excellence": install casing to at least 18 ft depth, surface seal,
sanitary well cap, pitless adapter
• Grouting requirements: Bentonite (minimum 20% solids for well seal)
• Surface seal: Minimum 18 ft depth; annular space grouted at least 10 ft for confined aquifers
• Sanitary well cap – prevents surface water entry
• Pitless adapter – eliminates frost heave, allows below-frost-line connection while maintaining
sanitary seal
• Annular space grouting to prevent vertical migration of contaminants
• Gravel pack design for sand control (filter pack for naturally unstable formations)
• Well development methods: surging (most effective for fine sand), air lift, overpumping, bailing
• Screen types: continuous slot (most open area), slotted casing, wire wrap, louvered
Pump Systems & Hydraulics (20-25%)
• Pump types: Submersible pump (most common for water wells), line shaft turbine, jet pump
(shallow and deep)
• Pump affinity laws: Flow (Q) varies directly with speed (N); Head (H) varies with N²; Power (P)
varies with N³
• Total Dynamic Head (TDH) = Static Lift + Friction Loss + Pressure Head (delivery pressure, if any)
• NPSH (Net Positive Suction Head) – critical for centrifugal pumps; not applicable to submersibles
• Motor sizing: 1 HP = 746 watts; service factor = ability to run above rated HP intermittently
• Cable sizing: voltage drop limits (max 3-5% for motors)
• Check valves – prevent backflow; required at pump discharge
• Torque arrestors – prevent twisting in the well
• Flow meters – required for compliance monitoring
Water Quality & Treatment (15-20%)
• Common contaminants: Iron, manganese, hardness, hydrogen sulfide (rotten egg odor)
• Treatment methods: Iron filtration (oxidation + filtration); Water softeners (ion exchange)
, Page 2 of 162
• Disinfection: Chlorination (shock chlorination for new wells, maintenance, after repairs); UV
disinfection (requires clear water)
• Reverse osmosis (RO) – removes TDS, nitrates, arsenic; produces wastewater
• Distillation – energy-intensive, removes most contaminants
• Corrosive water – addressed by pH adjustment or neutralizing filter (calcite)
• Coliform bacteria – causes gastrointestinal illness; requires disinfection
• Manganese – brown/black staining; lower secondary MCL than iron
• Aeration – removes hydrogen sulfide, radon, volatile organics, iron
• Bacterial iron – iron bacteria; requires disinfection and physical removal
• Filtration – turbidity removal
System Maintenance & Troubleshooting (15-20%)
• Pressure switch settings: Common 20/40, 30/50, 40/60 psi (typical differential of 20 psi)
• Pressure tank – provides drawdown volume; prevents short cycling
• Low yield troubleshooting: Pump cycles on/off rapidly (short cycling) → check pressure tank air
charge, bladder, or possible low yield
• Pump not delivering water: Check power, pressure switch, check valve, pump protection devices
(overload, low water cut-off)
• Air-locked pumps – common after repair, need to bleed air from discharge
• Galvanic corrosion – occurs when dissimilar metals are connected (use dielectric unions)
• Sand in water – well screen failure, gravel pack collapse, or overpumping
• Water level measurement – using electric sounder or air line
• Specific capacity = yield (gpm) / drawdown (ft) – declines with well age
Business & Professional Practice (5-10%)
• Customer service: written estimates, contracts, warranties
• NGWA Code of Excellence – ethical standards, transparency, responsible groundwater
stewardship
• Permit requirements – vary by state/local jurisdiction; contractor responsible for compliance
Question 1
A well driller is installing a new residential water well in an area with a shallow water table. According to
the NGWA Code of Excellence, what is the minimum depth to which casing must be installed to provide
a sanitary seal?
A) 10 feet
, Page 3 of 162
B) 18 feet
C) 25 feet
D) 50 feet
Answer: B
The NGWA Code of Excellence requires casing to be installed to a minimum depth of 18 feet, or through
unconsolidated material to competent bedrock, to prevent surface water contamination.
Question 2
During a pump service call, the technician finds that the submersible pump runs continuously but
delivers very little water. The pressure gauge shows pressure fluctuating between 20 and 30 psi. What is
the most likely cause?
A) The pressure tank is waterlogged (no air cushion)
B) The check valve is stuck closed
C) The pump motor is overheating
D) The pressure switch is set too high
Answer: A
, Page 4 of 162
A waterlogged pressure tank (bladder failure or lost air charge) causes rapid pressure changes and
short-cycling; the pump runs frequently without holding pressure.
Question 3
A well drilled into a confined aquifer must have the annular space sealed to prevent what?
A) Loss of aquifer pressure only
B) Vertical migration of contaminants from overlying formations into the confined aquifer
C) Corrosion of the casing
D) Entry of sand into the well
Answer: B
Annular space grouting (minimum 10 ft in confined aquifers) seals off the annulus to prevent water and
contaminants from moving vertically between aquifers.
Question 4
An irrigation well produces water that contains hydrogen sulfide (rotten egg odor). Which treatment
method is most effective for removing hydrogen sulfide from well water?
A) Water softener (ion exchange)
