Understanding the precipitation rate and the efficiency of the sprinkler system will allow correct irrigation scheduling for more efficient irrigation and water savings. This video will help you perform a catch cup (also know as a catch can) irrigation audit.
10 Steps to Success
1) Visually inspect your system for obvious problems. In many cases, an initial visual inspection can detect obvious problems that can be corrected, which will greatly improve the performance of the irrigation system. Turn on the system and watch it run. Are there broken sprinklers or obvious adjustments needed (heads not popping up all the way, clogged heads, or heads pointing in the wrong direction with water falling on the sidewalk instead of the lawn)? Are there obstructions preventing water from reaching the intended target (tree trunks, overgrown grass, weeds, or overhanging shrubs)?
2) Fix problems. Repair problems before proceeding further. If necessary, consult with a landscape contractor.
3) Map out the sprinkler heads. Locate all sprinkler heads and note the type and model. Sketch a map of the area and assign a number to each head on the map. Record the distance between heads and mark this on the map. For lawns with multiple irrigation zones, indicate which heads are in which irrigation zone.
4) Use catch cups or cans to collect and measure the water delivered by the irrigation system. Catch cans are receptacles of uniform size placed on the lawn area.
5) Run zone you're testing for 20 minutes. Caution! Do not perform the audit on a windy day (less than 5 mph wind is recommended).
6) Measure the volume in each container.
7) Calculate. Once the data are collected, calculate the average nozzle output by taking the total output divided by the total number of containers.
8) Convert the irrigation amount from Step 7 to in/hr, simply multiply the average by 3. (20 min x 3 = 60 mins)
9) Analyze. In order to determine how efficient the sprinklers irrigate, arrange the catch cup data from smallest to largest. Calculate the average volume of the lowest quarter (25% of the catch cups that collected the lowest amount of precipitation). If you used 12 catch cups for your irrigation audit, you need the average volume of the three cups that collected the least amount. Divide the lowest quarter average by the total average and then multiply by 100. This gives you the lowest quarter distribution uniformity in percent (%).
10) Enjoy! You now have the most accurate data on your block, and the intelligence of Rachio on your side. Enjoy your healthy lawn, while knowing you're using just the amount of water you need for your irrigation - and no more.