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Waterfall Pump Estimator

Estimate flow needed by width + desired sheet

This is a planning tool. Real output depends on lip design, elevation, pipe size, and head loss.
Estimated flow range:
Rule of thumb: many waterfall lips target 10–25 GPM per foot depending on the look.

How the Waterfall Pump Estimator Works

This calculator estimates the water flow needed for a pool waterfall based on the width of the spillway and the type of water sheet you want. Enter the waterfall width, choose inches or feet, and select a thin, medium, or thick sheet.

The result gives a rough gallons-per-minute range. The final pump must still deliver that flow after accounting for elevation, pipe length, fittings, valves, and other head loss.

Why Waterfall Width Matters

A wider waterfall needs more flow to create an even sheet from one side to the other. If the pump cannot supply enough water, the sheet may break apart, run heavier on one side, or cling to the spillway instead of projecting cleanly.

A thicker or farther-reaching sheet also needs more flow than a gentle decorative trickle.

What Changes Waterfall Performance

  • Spillway width and lip design.
  • Vertical lift from the pump to the waterfall.
  • Pipe diameter, length, and number of fittings.
  • Shared flow with returns, heaters, or other water features.
  • Debris or scale inside the spillway.

Common Waterfall Pump Mistakes

  • Choosing a pump by horsepower instead of the pump curve.
  • Ignoring total dynamic head.
  • Using undersized plumbing.
  • Trying to run several features from one small line.
  • Expecting a thick sheet from a low-flow spillway.

Frequently Asked Questions

How many GPM does a waterfall need?

Many residential waterfall lips use a rough range of about 10–25 GPM per foot, depending on the desired appearance and spillway design.

Why is the waterfall stronger on one side?

The spillway may be out of level, partially blocked, unevenly supplied, or receiving too little total flow.

Can the main pool pump run the waterfall?

Sometimes. The system must have enough available flow after filtration and other equipment needs are met. A separate feature pump may provide better control.

Why does the water cling to the wall?

Low flow, an unsuitable lip design, surface tension, or a dirty spillway edge can keep the water from projecting outward.

Pool Gal Pro Tip 💦

Do not size the pump by the pretty number on the box. Use the pump curve and make sure it can deliver the required GPM at the waterfall’s actual head.