Publication #ENH61

# How to Calibrate Your Sprinkler System1

L.E. Trenholm, J. Bryan Unruh, and J.L. Cisar2

Knowing the amount of water your sprinkler system applies to your landscape is an important step in efficient water use. Most people irrigate their landscape for a given number of minutes without knowing how much water they are really applying. This may lead to over- or under-watering, neither of which will benefit the landscape nor the environment. Calibrating will help you to apply the correct amount of water to your landscape. Whether you have an in-ground system or a hose and a sprinkler, the following steps will calibrate your system:

Figure 1.

Calibrating a Sprinkler System

[Click thumbnail to enlarge.]

1. Obtain several (5 to 10) coffee cans, tuna fish cans, or other straight-sided containers to catch the irrigation water. Containers need to be the same size and should be from 3 to 6 inches in diameter.

2. If you have an in-ground irrigation system, place the containers in one zone at a time. Scatter the cans at random within the zone (Figure 1). Repeat the entire procedure in every zone because there may be differences in the irrigation rates. If you use a hose-end sprinkler to water your landscape, place the containers in a straight line from the sprinkler to the edge of the watering pattern. Space the containers evenly.

3. Turn the water on for 15 minutes.

4. Use a ruler to measure the depth of water in each container. Note: The more precise the measurement, the better your calibration will be. For most cases, measurements to the nearest 1/8 inch are adequate.

5. Look for large differences in water amounts between cans. For example, if one has 1/2 inch or more and other cans are nearly empty, you know that your coverage is not uniform and your system needs to be inspected further.

6. Find the average depth of water collected in the containers (add up the depths and then divide by the number of containers).

7. To determine the irrigation rate in inches per hour, multiply the average depth of water times four. For example, if you collect an average of 1/4 inch in 15 minutes, and your target application rate is 1/2 inch, you will need to run your irrigation system for 30 minutes. Refer to Table 1 for additional calculations.

Table 1.

Time required to apply water for a given irrigation rate.

 Irrigation Rate (Amount of water applied per hour) ½" 1" 1½" 2" Total water to apply Minutes to run each zone ½" 60 30 20 15 ¾" 90 45 30 23

To calculate the time of irrigating for rates not listed in Table 1, use equation 1.

`                                 Equation 1.                         Amount of water  Minutes required       to be applied     X    60  for each zone     =  -------------------------------                        Your calibrated irrigation rate`

## Calibration Pointers

Calibrate the sprinkler system during the same time it is normally run, so that water pressure is similar.

Low water pressure can significantly reduce the amount and coverage of water applied by a sprinkler system.

Application rates normally should not exceed 1/2 to 3/4 inch of water per irrigation.

Most irrigation controllers can be adjusted for accurate time settings. Consult your operating instructions or local sprinkler company for details.

If you use a hose-end sprinkler, a mechanical timer and shut-off switch that attaches to the faucet will help make watering more efficient.

Avoid mixing sprinkler head types within the same zone. Mist heads apply more water than impact or rotary heads. Match sprinkler heads for uniform coverage. Most rotary heads come with several different nozzles to choose from. Make sure that the nozzles are matched.

Check the sprinkler system regularly. Replace broken sprinkler heads, clear clogged nozzles, and adjust the direction of spray as needed.

Be sure that irrigation water is not thrown on driveways, sidewalks, or roadways.

Use water efficiently; do not waste it.

For more specific information on turf irrigation, see factsheet ENH 9, "Watering Your Florida Lawn."

Figure 2.

Hose-End Sprinkler

[Click thumbnail to enlarge.]

### Footnotes

1.

This document is Fact Sheet ENH 61, a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: May 1991. Revised: January 2001 and April 2009. Please visit the EDIS website at http://edis.ifas.ufl.edu.

2.

L.E. Trenholm, associate professor, turfgrass specialist, Department of Environmental Horticulture, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, J. Bryan Unruh, associate professor, turfgrass specialist, West Florida Research and Education Center, Institute of Food and Agricultural Sciences, Jay, FL 32565, J.L. Cisar, professor, turf specialist, Ft. Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Ft. Lauderdale, FL 33314.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.