Well Volume Calculator

Knowing your well water volume is essential for several practical tasks. It tells you how much disinfectant (such as chlorine) is needed to treat the well, how much grout or sealant is required to plug it, and helps diagnose pump performance or recovery rate issues. Well drillers and water treatment professionals use this figure routinely.

The static water level is the distance from the top of the well casing down to the resting water surface when no pump is running. It is typically measured with an electronic sounder or a weighted tape measure. Your well driller's log will also record this figure at the time of drilling.

The calculator uses the standard cylindrical volume formula: Water Volume = π/4 × (diameter in feet)² × (Total Well Depth − Static Water Level). This gives the volume of the standing water column in cubic feet, which is then converted to gallons (1 ft³ = 7.48052 gallons) or liters.

When shock-chlorinating or disinfecting a well, industry guidelines typically recommend pumping out three times the standing water volume before testing water quality. This ensures fresh, untreated water from the aquifer has been fully flushed through the system, giving an accurate representation of the well's normal water quality.

The primary water volume calculation is based on the inner diameter of the well casing, which is the water-bearing portion of the well. The 'Total Well Volume' output uses the same diameter but over the full drilled depth (ignoring the static water level), which is useful for estimating plugging or grouting materials.

Yes. Select 'Metric' from the Display Units dropdown and enter your well diameter in centimeters, depths in meters. The calculator will return volumes in liters as the primary metric output alongside the gallon figure.

A static water level of 0 feet means the water surface is right at the top of the well casing — a flowing artesian well. In that case, the entire well depth is the water column, and the water volume equals the total well volume. The calculator handles this correctly.

The estimate is mathematically accurate for a straight, uniformly cylindrical well casing. Real-world factors such as irregular borehole walls, pump equipment occupying space inside the casing, and variations in the static water level due to seasonal changes or recent pumping can affect actual volumes. Treat the result as a reliable approximation rather than an exact measurement.