Water Feature Volume Calculator

Volume planning supports stable water quality and safe margins

Accurate volume helps dose conditioners, salts, and beneficial bacteria correctly, and it prevents overflow during rain. In warm, windy weeks, evaporation and splash can remove 2–8% of small pond volume. Using a 90–95% fill level preserves freeboard for waves, wildlife, and skimmer drawdown. It also supports predictable maintenance routines.

Shape selection improves estimates before excavation begins

Rectangular and circular basins are simplest, while ovals often match liner footprints better than rectangles. For an ellipse, area is π × (L/2) × (W/2), then multiply by depth. For organic outlines, the factor method converts a bounding rectangle into a realistic plan area.

Depth variation and displacement capture real‑world build details

Plant shelves and sloped bottoms make a single depth optimistic. The sloped option uses average depth, (shallow + deep)/2, which fits gentle grades. Displacement subtracts volume taken by rocks, gravel, baskets, and décor. Many features sit near 8–15%, while heavily rocked streams can exceed 20%.

Conversions and fill-time estimates turn numbers into a work plan

Liters are ideal for dosing and measuring losses, while gallons align with many retail labels. Fill time uses your hose flow (L/min or gpm) to forecast setup duration and water cost. For reference, 1 gpm is about 3.785 L/min. Example data: 2.4 m × 1.6 m × 0.55 m = 2.112 m³ raw; at 10% displacement and 95% fill, ≈1,806 L.

Turnover targets help right‑size circulation and filtration

The pump target equals volume × turnovers per hour. A common baseline is 1×/hour for ornamental ponds; waterfalls, fish loads, or strong surface movement may need more. Always compare the target to the pump curve at your head height, pipe length, bends, and filter restriction. If you use UV or a biofilter, verify the recommended flow range for that equipment.

1) How do I estimate an irregular pond accurately?

Use the irregular factor option. Enter maximum length and width, start with 0.70, then adjust the factor after a real fill test or when shelves and curves are finalized.

2) What displacement percentage should I use?

Lightly rocked basins often fall around 8–12%. Plant shelves, boulders, and gravel beds can push displacement to 15–25%. If unsure, choose 10% and refine after installation.

3) When should I choose sloped depth?

Pick sloped depth when the bottom transitions gradually from shallow to deep. The calculator uses the average of shallow and deep, which is a strong approximation for gentle grades and shelf zones.

4) Why does fill level matter?

Fill level reserves freeboard for rainfall, splash, and capillary rise in edging. Using 90–95% helps prevent overflow and liner exposure while keeping a stable operating volume.

5) Is the pump sizing result the final pump to buy?

It’s a target flow rate. Select a pump that meets the target after accounting for head height, pipe friction, bends, and filter resistance. Always check the manufacturer pump curve at your lift.

6) How can I verify the volume on site?

Use a water meter, calibrated container, or timed flow method during filling. Compare measured liters to the estimate and update displacement or factor so future top‑ups and dosing stay accurate.

7) Can I model a stream plus pond together?

Yes. Use Section A for the main basin and enable Section B/C for connected pools or a stream segment (often best as an irregular or custom area section). Total volume will combine all enabled sections.