Example of calculating irrigation run-time for any irrigation type, including drip, with the water meter-read test
We will be calculating the run-time for this zone in a young, mostly California native plant landscape.
If you have a drip irrigation system, or if you want to use an alternate method to test your spray or rotor system, you can use your water meter as a tool to determine how long to water. This method uses the area, in square feet, of the irrigation zone you are testing and some water use information from the meter before and after the test.
What you'll need
A measuring tape or measuring wheel (or taking measurements on google maps)
Pencil and paper to take measurements and notes on
A timer (or the stopwatch on your phone)
Run a zone of your irrigation system to determine exactly where it waters. Determine the area, in square feet, of that part of your landscape either by measuring or using the measuring functions in google earth
Measure the landscape zone and make a small drawing with measurements. Measuring by hand is usually the best and most accurate way, but if you have a large or awkward shaped area or do not want to do the math, you can try measuring using Google Maps measuring functions, though it may be more difficult to identify what areas are covered by a specific irrigation zone.
Calculate the area of each section of the landscape that is part of the irrigation zone. To calculate areas of shapes that are not perfect, break up zones into a series of simple shapes, rectangles, triangles, and circles.
Area of part A = 17’ x 5’ = 85 sq. ft
Area of part B = 22.5’ x 19’ = 427.5 sq. ft.
Total Area of section 1 = 512.5 sq. ft.
Find, open, and clean out your water meter box with gloves on
Find your water meter box. They are often located in the parking strip planted area along the street. This property has no parking strip landscape, so it is in the sidewalk.
With a gloved hand, use a tool to pry open the heavy concrete lid of the meter box through the center hole. Here a large flat head screwdriver is being used.
This is what it will look like inside the box. Before reaching in, check both the underside of the lid and inside the box for spiders. Black widow spiders sometimes like the dark dry conditions in meter boxes.
Record the numbers on the meter (“beginning meter reading”)
Lift open the lid on the water meter so you can read the face. You may need to clean if off to be able to read. A wet paper towel usually works well. This, and most meters read “cubic feet” of water. The directions here are for calculations with this type of meter. To begin the test, first write down the number displayed on the meter (40,597 cubic feet). This is your “beginning meter reading.”
Run the irrigation zone for 10-20 minutes, and record how long it ran
Manually run the irrigation zone you are testing for at lease 10 minutes. In this example, we ran the zone for 20 minutes. Make sure no water is running inside the house (laundry, faucets, toilets, showers, etc) during that time, because that would change the results. Write down how long you ran the zone. This number will be needed later.
To have your irrigation system run for this test, use the manual run function on your irrigation controller (timer). If you need to look up how to use it, check your manual. If you don’t have your manual, most manufacturers have downloadable versions of their manuals online because people often loose them! Write down the make and model number of your controller and do an internet search of the make and model and the word manual.
Record the numbers on the meter (“end meter reading”)
Check the meter one more time and record the numbers now showing. This will be your “end meter reading.” close the lid of the meter and carefully put the concrete lid back on the meter box.
Calculate irrigation run-time
Enter your information into the run-time calculator by meter reading and area to get your run-time for this irrigation zone.
Note: All fields must be entered to display correct results