Drip Run Time & How Long to Water
Schedules run time
Enter the crop's daily water need, emitter flow and emitter density to get the application rate in mm/hr and exactly how many minutes to run your drip system each day.
Set your drip system
Next: run the drip for 41.7 min each day to replace 5 mm of crop water use; split into pulses on sandy soils to cut deep drainage.
ET varies daily with weather and crop stage; recompute as the season progresses and verify emitter discharge against the catalogue at your operating pressure.
Drip run time — key facts
- Run time
- gross need ÷ application rate
- Application rate
- emitter flow × emitters/m²
- 1 L/m²
- = 1 mm depth
- Gross need
- ETc ÷ efficiency
- Drip efficiency
- ≈ 90%
- Too long
- wastes water below the roots
- Light soils
- split into short pulses
- Privacy
- Runs in your browser; nothing uploaded
Run the drip just long enough — no more, no less
A drip system should run each day only as long as it takes to replace the water the crop used. The trick is the application rate: emitter flow times emitters per square metre gives a wetting rate in mm/hr, because one litre over a square metre is one millimetre deep. Divide the daily depth the crop needs by that rate and you have the run time. Run any longer and the extra water drains below the roots, taking nutrients and pumping money with it.
This tool turns your crop's daily need and your emitter layout into the application rate, the gross depth after losses, the crop ET, and the exact run minutes. Use it to set your timer with confidence, then split long runs into pulses on sandy soils. Pair it with the Drip Irrigation, Emitter Spacing and Irrigation Scheduling tools to dial in a precise, water-efficient system.
Set the timer right
Exact daily minutes, no guesswork.
Stop wasting water
No water drained below the root zone.
Know your rate
Application rate in mm/hr from your emitters.
Match any layout
Change emitters per m² and minutes update.
Frequently Asked Questions
What is drip run time?+
Drip run time is how long your drip system needs to operate each day to replace the water the crop used. A drip system should run just long enough to refill the root zone — running longer pushes water below the roots where it is wasted, and running shorter leaves the crop short. This tool finds that exact duration.
How is drip run time calculated?+
Run time = gross water need ÷ application rate. The gross need is the crop's daily water use (ETc) divided by the system efficiency, expressed as a depth in mm. The application rate is how fast the system wets the ground in mm/hr. Dividing the depth you need by the rate you apply gives the hours (then minutes) to run.
What is the application rate of a drip system?+
The application rate is the emitter flow times the number of emitters per square metre, converted to a depth per hour. For example, 2 L/hr emitters at 4 emitters/m² apply 8 L/hr/m², which equals 8 mm/hr because one litre per square metre is one millimetre. A denser emitter layout or higher-flow drippers raises the rate and shortens run time.
Why does running drip too long waste water?+
Once the soil in the root zone is full, any extra water drains below the roots where the crop cannot reach it, carrying nutrients with it. Matching run time to the daily need keeps water and fertiliser in the root zone, saves pumping energy, and avoids waterlogging and leaching.
How do I get the daily water need?+
Use crop evapotranspiration (ETc) from a Pan Evaporation, Reference ET₀ or Crop ET tool for the current stage and weather, in mm/day. Divide by your drip efficiency (about 90%) to get the gross depth to apply. Enter that here and the tool returns the run minutes for your emitter layout.
Should I split the run into several short sets?+
On light or sandy soils, splitting the daily run into two or three shorter pulses keeps water in the root zone and reduces deep drainage, especially with high application rates. Heavier soils can usually take the full run in one set. The total minutes stay the same — you are just spreading them out.
Does emitter spacing change the run time?+
Yes. Closer emitter spacing means more emitters per square metre, a higher application rate, and a shorter run time for the same depth. Wider spacing lowers the rate and lengthens the run. The tool uses your emitters per m² directly, so changing the layout updates the minutes.
How often should I run the system?+
Most drip systems run daily or every other day because drip wets a small soil volume that holds little reserve. Multiply the daily need by the days between irrigations to set the depth per set, but keep intervals short on sandy soils and small root volumes.
Are these numbers exact for my field?+
They are accurate planning figures, but real emitter flow varies with pressure, temperature and clogging, and ETc shifts with weather and crop stage. Verify with a catch test or soil check, and adjust the daily need as the season changes.