When the average taxpayer hears the word “audit,” they tend to cringe. If they’ve been through a real IRS or bank audit recently, their mind starts reeling with all the possible negative outcomes – misunderstandings, transposed numbers, wrong forms, red ink – sometimes resulting in a wailing and gnashing of teeth. But if they’re honest about it, straightforward reflection will bring some positives to light as well. After all, doing things right the first time usually does. The same is true with turf irrigation systems.

At first, using an irrigation system is much like ignorant bliss. When it’s running well and spewing water onto the field, why worry about what might be wrong? It’s a good question with a simple answer: Things wear out and break. Additionally, since irrigation system parts are mechanical, it’s wise to take a good look at them to see if they’re worn or broken, just like everything else in the shop (aerators, mowers, spray rigs, etc.) could be.

Both simple and premarked catch cans can be utilized during an irrigation audit.

Basic routine

There are two ways to audit an irrigation system, much like IRS forms 1040, Schedule C and Schedule SE, where there’s a short and long version.

The first method is to simply take a quick look, where the steps are simple and few. The initial action is to turn on the system zone by zone and watch it run. The second step is to take notes about what you see, most likely obvious flaws such as heads not turning, overly coarse or fine mist being produced, heads not popping up at all and lack of head-to-head coverage. The final step is to fix the problems by replacing heads and nozzles and making simple adjustments. While not overly complex, this is a valuable and relatively short process. It identifies the big problems, allows for important routine maintenance and increases the efficiency of the system.

A pressure check of each zone and heads that contribute to problematic turf can reveal useful information.

Go the extra mile

In order to produce even greater efficiency, a full-blown audit is called for. A more detailed audit can be thought of as a report card for the system, with several categories of performance noted. In addition to the visual flaw correction of the basic routine described above, nozzle selection, water pressure, head spacing, run time and distribution uniformity are included in this long-form approach.

To learn more information about the inefficiencies that exist within the system, it’s critical to measure the output, not just look at it. Start by placing collection devices (catch cans or catch cups) in the sprinkler pattern. Irrigation supply and parts distributors are good sources of information about these integral tools. There are two guidelines that are commonly overlooked when measuring output:

  • Place enough catch cans in the spray pattern to account for all the water that will be placed on the turf, from all zones in the system. This usually means the zone that’s running at a given time and the zones on adjacent sides.
  • Place a catch can 2 to 3 feet away from each head and halfway in-between heads, at a minimum, while running the audit. If turf looks a bit off color, thin in a spot or is otherwise suspicious where there are no collection devices, put a catch can there also. When it comes to cans, it’s hard to use too many.

To learn more information about the inefficiencies that exist within an irrigation system, it’s critical to measure the output, not just look at it. Start by placing collection devices — catch cups — in the sprinkler pattern.

Distribution uniformity

Much of the positive outcome of an irrigation audit is a significant increase in the evenness of the sprinkler output, usually referred to as distribution uniformity. If you’re only doing one field, or want to see how the numbers and calculations work, do it by hand. This is done by measuring the amount of water collected in each can (usually easiest in millimeters), writing the numbers down on a chart or as-built drawing of the system, adding them together and dividing by the number of cans for an average.

Catch cans

If you’re going to be making several calculations, or have several fields to audit, it’s much more convenient to use a software program. One of the first was written by irrigation engineers at Cal Poly-San Luis Obispo; several others have developed over time, making improvements with each edition. As well, utilizing the services of a Certified Landscape Irrigation Auditor may prove to be a good move, especially when it comes time to recommending specific improvements to be made to the system.

Flagging heads is a first step that helps the auditor to know where to place catch cans.


Sometimes, the best things in life are a result of an experiment. Experimenting certainly works for inventors of new products as well as improvers of existing ones i.e. building a better mouse trap. Trimming the amount of applied water for an athletic field can benefit from some experimenting as well.

A wise and experienced irrigation auditor once was quoted as saying, “Want to do one more thing to increase efficiency and decrease water usage? Just trim.” This is a sound and often underutilized technique, however should only be utilized once the efficiency of the system has been improved to 75 percent or better. If trimming is implemented with a 40 to 65 percent efficient system, one that has not been through an irrigation audit and implemented suggested repairs, trimming or slightly reducing run times will usually produce highly undesirable results. This usually happens in the form of drought-stressed turf. If the distribution uniformity is acceptable, this is certainly an advisable final step.

Fortunately, the process is relatively simple. Start with a 5 or 10 percent target in mind and decrease the run time 1 or 2 percent each week until you notice moisture stress symptoms. So, if a zone is set to run for 25 minutes, a 5 percent reduction would be changing the run time on the clock by 1 minute, 15 seconds. A 10 percent trim for a zone set to run for 30 minutes would be 3 minutes. It’s doubtful that much, if any, noticeable difference between 27 and 30 minutes will be observed, yet the number of gallons of water to be saved is substantial, considering that the endeavor is to water an entire field (or complex of fields) measured in acres, compared to a home lawn measured in square feet. To be safe, monitor the crowns and root system to determine if any root loss or stand density has occurred after a reduction. A good sense of whether the reduced times can be had with your eyes, hands, feet and soil probes.

Examining roots periodically is wise to determine if any negative effects are occurring due to trims in run time.

Many options

Chances are that after an advanced audit, there will be many options that present themselves in terms of opportunities for improvement of a system. Keeping cost and field disruption in mind will help sift out the best selections to make, finding the sweet spot in terms of what you can afford and how long it will take to implement them.

In a 2009 study by Dr. Clark Throssel et. al., the changes/improvements that were found to be less disruptive were new sprinkler heads, new nozzles and software to control irrigation. The greatest disruptions were caused by installation of new main and lateral lines, new pump stations and new master controllers. In any event, more options are better than fewer.

Leaking valves are often a source of inefficiency and poor turf health.

Convincing to buy

Chances are good that the results of the audit might encourage you to be interested in system upgrades, which, of course, cost money. So, who will fork over the cash to implement the new equipment? Probably the owner of the facility. Will they be ready to spend money with just a casual mention of the problems that exist? Probably not. You’ll likely need to convince them to open their checkbook.

The best opportunity for success in convincing the checkbook to open is by laying out the state of the current system – water used, repairs needed to maintain it, broken parts, need to install parts/equipment that are no longer being manufactured and the current distribution uniformity. After the raw information has been presented, an appeal should be made to the decision maker based on their own bias. There are several possible ones to appeal to, but the ones that make the most sense for this application are an appeal for money savings, an appeal based on emotions (fear, concern, worry, etc.) and/or an appeal to realize the public relations value of the improvements. Knowing which one, or which combination, of appeals is the most likely to be effective is challenging, but certainly worth the effort.