Waterfall Pump Flow Calculator
The pump flow a waterfall or pond spillway needs for a trickle, a sheet or a heavy fall.
Result
1,600 gphEstimate
A retailer’s rule of thumb for how the fall looks; read the pump’s chart at your lift, and allow for the pipe run.
- Lift to read on the pump chart
- 4 ft (1.2 m)
- Before pipe and fittings: add the maker’s allowance for your run
- Note
- Choose a pump whose chart shows at least this flow at this lift plus your pipe run. Longer pipe, bends and filters take flow away.
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Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use the Waterfall Pump Flow Calculator
- Measure the width of the spillway lip the water pours over.
- Choose the look you want, or enter your own flow for a width from a maker's guide.
- Enter the height from the pond's surface to where the water comes out.
- Read the flow, then find a pump whose chart shows at least that flow at that height plus your pipe run.
How it is calculated
flow = spillway width × flow per width for the look trickle 50, sheet 100, heavy fall 200 US gal per hour per inchlift = height from the pond surface to the top of the fallsturnover = pond volume ÷ flowThe flows per inch are TotalPond’s retail guidance, not a standard, and the page names them as such. How a fall looks also depends on the lip: a smooth, flat lip makes a clean sheet with less water than a rough stone edge.
Choosing the pump
Take the flow and the lift to the pump maker’s performance chart. The right pump shows at least that flow at your lift plus an allowance for the pipe, fittings and any filter in the line. A pump that is too small leaves the spillway dribbling; one far too big can push water over the sides of a stream.
With your numbers
- Flow = 16 in × 100 gph per inch = 1,600 gph
Quick reference
A retailer’s rule of thumb for how the fall looks; read the pump’s chart at your lift, and allow for the pipe run.
| Job | Pump flow needed at the falls |
|---|---|
| 16 in spillway, sheet | 1,600 gph |
| 12 in spillway, sheet | 1,200 gph |
| 24 in spillway, heavy fall | 4,800 gph |
| 8 in spillway, trickle | 400 gph |
| 24 in at 1,800 gph per foot | 3,600 gph |
| 40 cm spillway, sheet | 5,961 L/h |
| 60 cm spillway, heavy fall | 17,884 L/h |
Where the numbers come from
The fixed figures this calculator relies on, and the published source each one was checked against. How the calculators are built and checked
3 sources
TotalPond, "Choosing the right TotalPond Waterfall Pump is easy": after 100 GPH per inch for a sheet, "Divide by two for a 'trickle' look." https://totalpond.com/pages/waterfall-pumps
Used for
- Pump flow for each inch of spillway width for a trickle: half the sheet figure, 50 US gallons per hour per inch, TotalPond’s retail guidance.
TotalPond, "Choosing the right TotalPond Waterfall Pump is easy": "For every 1 in. of spillway width, you need 100 GPH (gallons per hour) flow to achieve a 'sheet' look", with the example of a 16 in spillway at 1,600 GPH. https://totalpond.com/pages/waterfall-pumps. Russell Watergardens, "What Size Pump Do I Need For My Waterfall?", gives the same 100 GPH per inch for a basic waterfall and 1,800 GPH per foot (150 per inch) for an average one, https://russellwatergardens.com/pages/waterfall-flow-rates.
Used for
- Pump flow for each inch of spillway width for a sheet of water over the lip: 100 US gallons per hour per inch, TotalPond’s retail guidance.
TotalPond, "Choosing the right TotalPond Waterfall Pump is easy": after 100 GPH per inch for a sheet, "Multiply by two for a 'Niagara' look." https://totalpond.com/pages/waterfall-pumps. Russell Watergardens also gives 200 GPH per inch "for more noise and white-water", https://russellwatergardens.com/pages/waterfall-flow-rates.
Used for
- Pump flow for each inch of spillway width for a heavy fall: twice the sheet figure, 200 US gallons per hour per inch, TotalPond’s retail guidance.
Common questions about the Waterfall Pump Flow Calculator
- What size pump do I need for a waterfall?
- Size it by the width of the spillway and the look you want. TotalPond’s guide gives 100 gallons per hour for every inch of spillway for a sheet of water, half that for a trickle and double for a heavy fall. A 16 inch spillway needs about 1,600 gallons per hour for a sheet, delivered at the height of the falls.
- Why does the height of the waterfall matter?
- A pump moves less water the higher it has to push it. Every pump has a chart of flow against lift, often called head, and a pump sold as 2,000 gallons per hour may deliver far less at the top of a 5 ft fall. Read the chart at your height, not the number on the box.
- Does the pipe change the flow?
- Yes. Long runs, narrow pipe, bends, valves and filters all resist the flow and act like extra height. Pump makers publish charts or calculators that add this for their pipe sizes; this page leaves it out, so allow some margin or use the maker’s figure for your run.
- Is there another rule for waterfall flow?
- Several. Russell Watergardens gives 1,800 gallons per hour for each foot of width for an average waterfall, which is 150 per inch, and more for white water. Choose "My own flow per width" and enter any maker’s figure to use it instead.