Well Volume Calculator
Calculate how many gallons of water your well currently holds, understand static water levels, and plan pumping schedules.
Measure from the water surface to the well bottom.
Depth of water before pumping (optional).
Cross-sectional area: 12.57 ft²
Volume: 251.33 ft³
Water available: 1880 gallons (7117 liters)
Static water volume: 940 gallons
Drawdown reserve: 940 gallons (after static level drops)
How to Use This Calculator
Measure water depth
Drop a weighted line until it hits water, mark the wet point, and measure the submersion length.
Capture well dimensions
Measure diameter (or length and width) at the water surface. Use accurate data from drilling logs if available.
Plan drawdown
Static water level helps estimate how much water remains after pumps run for a while.
Formula
Cylindrical Area = π × (Diameter ÷ 2)²
Rectangular Area = Length × Width
Volume (ft³) = Area × Water Depth
Gallons = Volume × 7.48052
Liters = Gallons × 3.78541
Example: 4 ft diameter, 20 ft water → 12.57 ft² area × 20 = 251 ft³ → 1,876 gallons.
Well Management Tips
- Check water level quarterly to monitor aquifer health.
- Keep pumps above the sediment layer (leave at least 5 ft clearance).
- Use drawdown data to size pressure tanks for rural water systems.
- Disinfect wells after significant level changes or maintenance.
Frequently Asked Questions
What is static water level?
It’s the height of water in the well when pumps are off. Use it to understand normal resting water volume.
How accurate is this calculator?
Accurate measurements yield precise gallons. Irregular well shapes or sediment layers may affect results.
Can I plan irrigation from these numbers?
Yes—convert gallons to inches of water per acre or per zone. Adjust for pump flow rates and recharge time.
What if the well tapers?
Use the narrowest diameter for conservative estimates, or calculate multiple sections and sum volumes.