The recommended water flow for a waterfall depends on the width of the spillway and the desired appearance of the water.
- Standard waterfall flow: 1,500 gallons per hour (GPH) per foot of waterfall width, or approximately 19,000 liters per hour (LPH) per meter.
- Heavy waterfall flow: 3,000 GPH per foot of waterfall width, or approximately 38,000 LPH per meter, for a stronger, more dramatic waterfall.
How to calculate waterfall flow
Multiply the width of the waterfall spillway by the recommended flow rate.
Example: A waterfall with a 2 ft (0.61 m) wide spillway requires approximately:
- Standard flow: 2 × 1,500 = 3,000 GPH (11,356 LPH)
- Heavy flow: 2 × 3,000 = 6,000 GPH (22,712 LPH)
Measure only the width where the water flows over the spillway, excluding the surrounding rocks.
Important: These calculations estimate the water flow needed at the waterfall, not the pump's maximum rated flow. When selecting a pump, account for the waterfall's height, pipe length, fittings, and other restrictions that reduce water flow.