Water Feature Flow Calculator

Every type of water feature needs a completely different flow-rate formula, because the visual effect each one produces comes from a different physical mechanism. This calculator branches on the feature type you pick: waterfalls use a rule-of-thumb rate of 100 gallons per hour for every inch of spillway width, scaled by your chosen water thickness, since a wider lip or a heavier "sheet" both need proportionally more water to look full rather than sparse. Sheer descent (spillover) features use a higher 150 GPH-per-inch baseline, since that clean glass-like curtain effect needs more volume per inch than a rougher waterfall edge to stay unbroken. Fountains instead scale off spray height alone — about 50 GPH per foot of desired height — since fountain nozzles trade flow for pressure rather than sheet width.

Once the required flow is set, the calculator adds a flat 20% oversizing margin to size the pump itself (accounting for head pressure it hasn't directly measured), recommends pipe diameter from flow-rate breakpoints (3/4" under 500 GPH, up through 2" above 2000 GPH), and estimates electrical cost from a rough 100 watts per 500 GPH assumption run 10 hours a day at $0.13/kWh. Keep in mind these are rule-of-thumb multipliers pulled from common landscape-design guidance, not a fluid-dynamics simulation of your specific feature geometry — actual required flow can vary with nozzle design, water texture goals, and how far water has to travel horizontally before it drops. Use the results to shop pump specs in the right ballpark, then fine-tune with the manufacturer's own head-loss curve for your exact pipe run.