DRAINAGE CALCULATOR
Sump pit volume
How much water occupies a cylindrical basin at a given depth?
The calculation.
Gallons = π × (inside diameter inches ÷ 24)² × (water depth inches ÷ 12) × 7.48051948.
A worked example.
A 24-inch inside diameter and 24-inch water depth gives about 47.0 gallons.
What the number means.
Assumes a straight-sided cylinder and does not subtract the volume occupied by a pump or other equipment. Water depth is not necessarily basin height. This does not size a pump or predict cycling, groundwater inflow or storm performance.
