Calculator inputs
Example data
| Scenario | Area (m²) | Net depth (mm) | Efficiency (%) | Gross volume (L) | Flow (L/min) | Runtime (min) |
|---|---|---|---|---|---|---|
| New sod establishment | 500 | 10 | 75 | 6,667 | 80 | 83.3 |
| Dust control (light) | 1,200 | 3 | 65 | 5,538 | 120 | 46.2 |
| ET schedule (hot day) | 800 | ET0×Kc×Days | 80 | — | — | — |
Example values are illustrative. Always verify local requirements and site conditions.
Formula used
- Net depth (ET mode): NetDepth(mm) = ET0(mm/day) × Kc × Days
- Gross depth: GrossDepth(mm) = NetDepth(mm) ÷ (Efficiency/100)
- Net volume: NetVolume(m³) = Area(m²) × NetDepth(mm)/1000
- Gross volume: GrossVolume(m³) = Area(m²) × GrossDepth(mm)/1000
- Runtime from flow: Minutes = GrossVolume(L) ÷ Flow(L/min)
- Runtime from precipitation: Hours = GrossDepth(mm) ÷ PrecipRate(mm/hr)
How to use this calculator
- Pick a mode: per-event depth, or ET-based schedule.
- Enter the irrigated area and select the correct unit.
- Set efficiency to reflect wind, distribution, and overspray.
- For per-event mode, enter the net depth you want applied.
- For schedule mode, enter ET0, Kc, and days between events.
- Add flow rate or precipitation rate to estimate runtime.
- Press Calculate to view results, then export CSV or PDF.
Professional article
1) Why irrigation matters on active sites
Temporary irrigation supports erosion control, dust suppression, and plant establishment on disturbed soils. Many projects specify surface wetting during grading and deeper watering for newly placed sod or seed. Converting target depths into volume helps crews plan tanker loads, hydrant draws, and daily watering routes without guesswork.
2) Converting depth to volume accurately
Depth represents a thin layer of water spread over an area. A 10 mm application equals 10 liters per square meter. The calculator converts any area unit to square meters, then multiplies by depth to produce cubic meters and liters. This method scales from small planter beds to multi‑acre staging zones.
3) Accounting for efficiency and losses
Wind drift, overspray, nonuniform coverage, and surface runoff reduce beneficial water. Efficiency adjusts the net depth (what you want the ground to receive) into gross depth (what you must apply). Typical field efficiencies range from 60% for windy hose watering to 80–85% for well‑tuned sprinklers and low wind conditions. Even small gains in efficiency can save thousands of liters on large pads.
4) Runtime planning with flow rate
Flow‑based runtime links gross volume to your available supply. When you enter total flow, the tool estimates minutes required to deliver the calculated liters. This is useful for pump sizing, manifold balancing, and shift planning. If runtime looks excessive, reduce area per zone or improve distribution efficiency.
5) Runtime planning with precipitation rate
Spray devices are often rated by precipitation rate (mm/hr or in/hr). Using gross depth and precipitation rate gives a second, independent runtime check. High precipitation on tight soils can cause runoff, so shorter cycles with soak periods may be safer. Keep application rates near soil intake capacity.
6) Scheduling from ET and site demand
In schedule mode, net depth is based on ET0 × Kc × days between events. ET0 comes from local weather stations, while Kc reflects surface type: turf commonly 0.7–1.0, while bare soil or dust control may use lower effective values. Shorter intervals reduce stress and surface cracking.
7) Practical data checks before mobilizing
Validate inputs with quick field observations. Measure nozzle output into a bucket to confirm flow, and perform a catch‑can test to estimate precipitation rate and uniformity. Confirm that hoses, valves, and sprinklers can sustain the target flow without pressure collapse. Recheck after equipment changes or leaks.
8) Documenting quantities for compliance
Many contracts require logs of water usage for sustainability reporting, hydrant permits, or dust‑control plans. Exporting CSV supports daily totals, while the PDF is handy for supervisors and inspectors. Record the date, zone, gross liters, and runtime so adjustments are traceable across changing site conditions.
FAQs
What is the difference between net and gross depth?
Net depth is the water you want the surface to receive. Gross depth is what you must apply after accounting for efficiency losses like wind drift, overspray, and runoff. Gross depth is always equal to or greater than net depth.
Which mode should I use: per‑event or ET schedule?
Use per‑event when a spec calls for a fixed application depth, such as sod establishment or dust control. Use ET schedule when you have ET0 data and want a climate‑driven depth based on Kc and irrigation interval.
What efficiency value is reasonable on construction sites?
Hand watering and water trucks can be 50–70% depending on wind and operator control. Portable sprinklers often reach 70–85% when pressure and spacing are correct. If you’re unsure, start at 75% and refine with field observations.
How do I estimate flow rate if I only have hose size?
Measure it. Time how long it takes to fill a known container, then convert to L/min or gpm. Repeat a few times and average. Flow can change with hydrant pressure, elevation, and simultaneous site use.
My precipitation rate is high—what should I do?
High precipitation can exceed soil intake, causing runoff and wasted water. Reduce runtime per cycle, add soak time between cycles, use larger spacing or different nozzles, or split the area into more zones to lower instantaneous application.
Does the calculator include rainfall?
No. The results are irrigation quantities only. If rainfall is expected, subtract an estimated effective rainfall depth from the net depth before calculating, or reduce the irrigation interval. Always follow local stormwater and dust‑control requirements.
Why do my flow‑based and precipitation‑based runtimes differ?
They rely on different inputs and assumptions. Flow‑based uses total delivered volume, while precipitation‑based uses device application rate over the area. Differences often indicate nozzle rating errors, uneven coverage, or incorrect active irrigated area.
Use these estimates to reduce waste and rework daily.