Pond Waterfall Flow Calculator
Free Calculator
Calculate waterfall flow for your koi pond
Estimate the delivered flow needed at a waterfall spillway based on its width and the visual effect you want. The result can be carried into the pond pump calculator.
Waterfall spillway
Estimated delivered flow at waterfall
This is the flow you want delivered at the waterfall after head and plumbing losses. A pump's zero-head rating will usually need to be higher.
Choosing a waterfall flow
The presets are planning rates per foot of spillway width. A smooth constructed weir can form a sheet at lower flow than an irregular rock edge, while a dramatic whitewater effect needs substantially more water. Use the appearance closest to your goal, then verify the result against the actual spillway and pump curve.
Calculator note
Rock shape, spillway lip, drop height, stream geometry, and plumbing all change the appearance. This calculator estimates waterfall flow only; use the Pond Pump Size Calculator to account for total dynamic head.