Enter waterfall and plumbing details
Use the intensity preset for quick sizing, or set a custom target rate.
Example data table
Use these examples to validate your setup and expected outputs.
| Scenario | Width | Target rate | Lift | Pipe | Fittings | Base flow | Typical head |
|---|---|---|---|---|---|---|---|
| Small patio feature | 12 in | 150 gph/in | 5 ft | 20 ft @ 1.5 in | 4×90°, 1 valve | 1,800 gph | ~6–8 ft |
| Wide spillway | 24 in | 200 gph/in | 6 ft | 35 ft @ 2 in | 6×90°, 1 valve | 4,800 gph | ~8–11 ft |
| Compact metric setup | 40 cm | 28 lph/cm | 1.5 m | 12 m @ 40 mm | 6×90°, 1 valve | 1,120 lph | ~1.8–2.5 m |
Formula used
This calculator combines flow-per-width sizing with head loss and power estimation.
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Base flow target
Flow is sized by spillway width:
Q = W × R(Q flow, W width, R target flow rate per width) -
Friction head loss (Hazen–Williams)
Equivalent length from fittings is added to the straight pipe length. Then Hazen–Williams estimates friction loss for water.
Imperial form:h_f = 4.52 × L × Q^1.85 / (C^1.85 × d^4.87)(hf in ft, L in ft, Q in gpm, d in inches)
Metric form:h_f = 10.67 × L × Q^1.852 / (C^1.852 × d^4.871)(hf in m, L in m, Q in m³/s, d in m) -
Total dynamic head
H = H_static + h_f(static lift plus friction losses) -
Power and energy
Hydraulic power:P_h = ρ g Q H
Electrical estimate:P_e = P_h / η
Daily energy:E = (P_e/1000) × hours
Metric: 90° elbow 1.5 m, 45° elbow 0.9 m, ball valve 2.5 m, check valve 3.5 m.
How to use this calculator
- Select units that match your tape and pipe markings.
- Choose an intensity preset, or switch to custom target.
- Enter spillway width and confirm the target rate.
- Add vertical lift and straight pipe length accurately.
- Enter pipe inside diameter and pick a material factor.
- Count fittings and valves, then enter your runtime.
- Click calculate and select a pump that meets the flow at head.
Professional guidance
Design targets for a consistent sheet
Waterfall appearance is driven by flow per unit width. A gentle sheet reduces splash and noise, while a heavy sheet increases sound and visual sparkle. Use a target that matches your spillway geometry, stone texture, and desired “whitewater” level. Wider spillways scale flow linearly.
Accounting for total dynamic head
Pumps are rated at specific head values, not at zero lift. Total dynamic head combines static lift plus friction losses from pipe and fittings. Long runs, small diameters, and restrictive valves can add meaningful head, reducing delivered flow. This calculator estimates friction to improve selection.
Pipe diameter and material impacts
Larger pipe diameters reduce velocity and friction losses, helping the pump deliver closer to its rated curve. Smooth interior materials typically produce lower losses than rough or aged lines. If your result shows high friction head, upsizing pipe often costs less than upgrading the pump.
Selecting a pump from performance curves
After calculating a base flow target, select a pump that meets that flow at the calculated head. Add headroom to cover real installation losses, elevation variability, and debris buildup. If using a filter, UV, or manifold, include their losses in your planning for best performance.
Energy planning and maintenance considerations
Electrical cost depends on run hours and efficiency. For long daily runtime, prioritize efficient pumps and minimize losses through clean plumbing. Inspect intake screens, flush lines, and keep valves fully open when possible. Stable flow improves aeration and helps maintain clear pond water.
FAQs
1) Why does my waterfall look weak even with a big pump?
High head loss from small pipe, long runs, fittings, or filters can reduce delivered flow. Verify the pump curve at your total head and reduce restrictions where possible.
2) What intensity should I pick for a natural stream look?
A gentle to medium target usually works for natural-looking flow. Use gentle for quieter sheets and less splash, and medium when you want stronger sound and more surface texture.
3) Should I oversize the pump?
Moderate headroom helps cover real-world losses and seasonal buildup. Oversize too much and you may waste energy or create excessive splash. Aim for a pump that meets target flow at head with a small margin.
4) How accurate is the friction calculation?
It is an engineering estimate based on standard friction relationships and simplified fitting losses. It is suitable for planning and comparison. Always confirm final selection with the pump’s published curve.
5) What pipe diameter is best for higher flows?
Larger diameters generally perform better for higher flows by lowering velocity and friction. If friction head is a large share of total head, upsizing pipe can significantly improve delivered flow.
6) Do valves and check valves matter a lot?
Yes. Each valve adds loss, and partly closed valves add much more. Use low-loss fittings and keep control valves fully open when possible. Add check valves only when needed for backflow control.
7) How can I lower running costs?
Reduce head loss with larger pipe, fewer tight turns, and clean screens. Choose efficient pumps, run fewer hours, or use a timer. Keeping plumbing clean helps maintain flow without increasing power.