Perth sandy soils
Sandy soils absorb 12–25mm/hr. A PR above 20mm/hr risks runoff — cycle-and-soak is recommended for high-rate zones.
Waterwise target
Water Corporation recommends 6–10mm per session for established lawns on sandy Perth soils, applied twice weekly.
Spacing method vs zone area
Use the spacing method when designing a new zone or auditing head placement. Use zone area when you know the total m² and head count but not individual spacing.
Triangular spacing
Triangular patterns deliver 13% lower PR than square at the same spacing — useful if you're close to the runoff threshold and can't reduce flow further.
Precipitation rate explained
What's the formula?
For square spacing: PR (mm/hr) = (flow in L/min × 60) ÷ (spacing² in m²). For triangular: divide by 0.866 × spacing². For rectangular: divide by row × column spacing.
How accurate are the head flow presets?
The presets are typical mid-pressure values. For accurate design, use the flow curves from the manufacturer's data sheet at your measured operating pressure. Small pressure variations can shift flow significantly on fixed-spray nozzles.
Want to verify with a field measurement?
Use the Catch Can Test to measure actual application rate from your heads — much more accurate than calculated PR for existing systems.