NGWA GENERAL DRILLING CERTIFICATION
PRACTICE EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A | INSTANT
DOWNLOAD PDF
1. What is the primary purpose of water well drilling?
A. Oil extraction
B. Accessing groundwater for use
C. Soil stabilization
D. Mineral exploration
Groundwater wells are drilled to reach usable underground
water sources.
2. Which formation is most likely to yield high groundwater flow?
A. Clay
B. Shale
C. Sand and gravel
D. Granite
Sand and gravel have high porosity and permeability.
3. Porosity refers to:
A. Strength of rock
B. Amount of void space in material
, C. Water pressure
D. Depth of formation
Porosity measures how much open space exists to store water.
4. Permeability describes:
A. Water quality
B. Ability of material to transmit water
C. Depth of aquifer
D. Rock hardness
High permeability allows groundwater to flow easily.
5. An unconfined aquifer is characterized by:
A. Pressure greater than atmospheric
B. Water table as upper boundary
C. Overlying impermeable layer
D. No recharge
Unconfined aquifers are open to the surface and recharge
directly.
6. A confined aquifer is usually found:
A. At the surface
B. Above the water table
C. Between impermeable layers
D. Only in bedrock
Confining layers trap water under pressure.
7. The static water level is:
A. Pumping level
B. Maximum drawdown
C. Natural level when not pumping
, D. Screen depth
It represents equilibrium groundwater level.
8. Drawdown is defined as:
A. Pump size
B. Well diameter
C. Difference between static and pumping water level
D. Total depth of well
Drawdown indicates how much the water level drops during
pumping.
9. Specific capacity is measured as:
A. Feet per hour
B. Gallons per minute per foot of drawdown
C. PSI per foot
D. Inches per minute
It evaluates well performance efficiency.
10. Which drilling method is best suited for unconsolidated
formations?
A. Cable tool
B. Rotary mud drilling
C. Air rotary only
D. Diamond coring
Mud rotary stabilizes loose formations.
11. Air rotary drilling is most effective in:
A. Clay
B. Hard rock formations
C. Silts
PRACTICE EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A | INSTANT
DOWNLOAD PDF
1. What is the primary purpose of water well drilling?
A. Oil extraction
B. Accessing groundwater for use
C. Soil stabilization
D. Mineral exploration
Groundwater wells are drilled to reach usable underground
water sources.
2. Which formation is most likely to yield high groundwater flow?
A. Clay
B. Shale
C. Sand and gravel
D. Granite
Sand and gravel have high porosity and permeability.
3. Porosity refers to:
A. Strength of rock
B. Amount of void space in material
, C. Water pressure
D. Depth of formation
Porosity measures how much open space exists to store water.
4. Permeability describes:
A. Water quality
B. Ability of material to transmit water
C. Depth of aquifer
D. Rock hardness
High permeability allows groundwater to flow easily.
5. An unconfined aquifer is characterized by:
A. Pressure greater than atmospheric
B. Water table as upper boundary
C. Overlying impermeable layer
D. No recharge
Unconfined aquifers are open to the surface and recharge
directly.
6. A confined aquifer is usually found:
A. At the surface
B. Above the water table
C. Between impermeable layers
D. Only in bedrock
Confining layers trap water under pressure.
7. The static water level is:
A. Pumping level
B. Maximum drawdown
C. Natural level when not pumping
, D. Screen depth
It represents equilibrium groundwater level.
8. Drawdown is defined as:
A. Pump size
B. Well diameter
C. Difference between static and pumping water level
D. Total depth of well
Drawdown indicates how much the water level drops during
pumping.
9. Specific capacity is measured as:
A. Feet per hour
B. Gallons per minute per foot of drawdown
C. PSI per foot
D. Inches per minute
It evaluates well performance efficiency.
10. Which drilling method is best suited for unconsolidated
formations?
A. Cable tool
B. Rotary mud drilling
C. Air rotary only
D. Diamond coring
Mud rotary stabilizes loose formations.
11. Air rotary drilling is most effective in:
A. Clay
B. Hard rock formations
C. Silts
