New Year’s Resolution: An Irrigation Audit

By Lisa Rogers, Fort Bend County Master Gardener

It’s that time of year when we’re all making New Year’s Resolutions. Most of these resolutions have to do with making healthy lifestyle changes. By February most of us will be discouraged because we couldn’t resist that piece of chocolate or that coke. And, well the gym was just too crowded in January! Why not make a resolution to routinely audit your irrigation system instead? The benefits of routine irrigation audits could include saving money, water conservation, healthier landscapes and a sense of pride and accomplishment.
An irrigation audit includes three activities; Inspection, Performance Test and Controller Adjustments. The inspection involves walking your landscape zones and making notes of any problem areas. Things to look for are soggy landscapes or standing water, and dead or dry areas in the turf or landscape. Next, you will turn on your irrigation system to test mode. This setting will run each zone for 2 minutes, which allows enough time to walk through each zone during operation. If your controller does not have a test mode you can manually run through the zones. At each zone look for broken, missing or sunken heads and misaligned spray patterns. Also look for insufficient or excessive operating pressure. Large water droplets and insufficient stream length, or throw, indicates low water pres-sure while excessive misting that evaporates quickly indicates high water pressure.
Performance testing of your irrigation system is done to determine precipitation rate and distribution uniformity. A Catch Can Test (CCT) is the best way to check performance. For the CCT you will need 1-2 dozen commercially available catch cans or tuna/cat food cans and a ruler. Begin with Zone 1 by turning on the Irrigation System and mark all of the sprinkler heads. Then place catch cans in a grid-like pattern throughout the zone every 3-5 ft. Document on a piece of paper the placement of all the catch cans. Turn on Zone 1. Keep track of time. After measurable amount of water has fallen measure the water depth in tenths of inches and record these values and how long (in minutes) the zone operated. Repeat the procedure for each zone. Using the data from the CCT the precipitation rate for each zone can be determined using the following equation: Precipitation rate= (average catch can water depth/test run time) X 60. The precipitation rate per zone will be in inches per hour. You can use this data to make changes in your controller settings. If you have a rain sensor don’t for-get to check for proper functioning by manually pouring water over sensor and making sure the controller responds by shutting down irrigation.
The last part of an irrigation audit involves making adjustments in your controller settings. It is the goal to run your irrigation system to meet your landscape needs in the most efficient manner. To do this make run time adjustments seasonally. Lawns typically need 1-2 inches of water per week during the summer months with less during spring and fall. If you don’t have a rain sensor you will need to manually turn your system off during periods of measurable rainfall. Run your irrigation during the early morning hours before the sun and wind will cause evaporation rates to increase. If you have runoff during irrigation cycles set your controller to “Cycle & Soak” or manually run your system for shorter times but more often to control runoff.
At a minimum, make a resolution to audit your irrigation system 4 times per year at the change of seasons. Don’t forget to correct problem areas you find during your audit. Then sit and relax with-out guilt and with some chocolate when you fulfill your resolution and reap the savings from conservation of water and enjoy your view!

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