How Long Should I Run Drip Irrigation?
Calculate runtime from emitter flow, spacing, and the water depth you want to add to a garden bed.
Published by ThriveThyme
irrigation drip watering
Runtime depends on delivery rate
Choose the water amount still needed after considering rainfall and soil moisture, then divide it by the system's application rate. A timer setting borrowed from a different drip system can deliver a very different amount.
For uniformly spaced inline emitters, Utah State calculates inches per hour as emitter flow in gallons per hour times 231, divided by emitter spacing and line spacing, both in inches. The Drip Irrigation Calculator applies that formula and converts the result into total gallons and minutes.
A worked example
With 0.9-gallon-per-hour emitters spaced 12 inches apart and lines 18 inches apart, the calculated rate is about 0.963 inches per hour. Adding half an inch takes about 31.2 minutes. This is arithmetic for that setup, not a recommendation that every bed needs half an inch.
Check actual wetting and operating pressure. Water pooling at the surface means delivery and infiltration are not matching well. Split the total into shorter runs if needed, then inspect again.
Next Steps
Measure your system output and save the result in the calculator. For tree establishment in cold weather, use Fall and Winter Watering.