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Irrigation Auditing

Dear Lawn Sprinkler Services Customer

As you all have probably heard, the City of Wichita Water Department has begun discussions on ways to conserve water and how to lower the amount of water used for outdoor purposes. This is a huge issue and can potentially have a major impact on our industry and also potentially change our cultural views about landscaping. We at Lawn Sprinkler Services want to be a part of the solution, so we are proactively looking at ways that we can lower the amount of water used on lawns and try to improve the efficiency of the sprinkler systems we install and maintain. Anticipating this move by the water department, Lawn Sprinkler Services spent the winter of 2012-2013 researching better sprinkler system design principles and comparing sprinkler head uniformities to see if what we are doing works, and what can be done to a sprinkler system to allow it to use less water and still keep the lawn as green and healthy (or healthier) than it is now.

We began by looking through our customer list and choosing 20 sprinkler systems that we felt were a reasonable cross section of the type of sprinkler systems we see in the Wichita Area. We then performed an audit of the coverage in these systems. We chose a few systems that we had installed, some that we did not install but knew were really bad, and others we felt were pretty good and randomly chose some that we did not really have an opinion on. It was incredible the differences in the quality and efficiency of the sprinkler systems we service.

Auditing, Efficiency, Uniformity what do these terms mean? Since the sprinkler heads in an underground sprinkler system cannot be physically picked up and moved around it is important that the heads are placed so that the water is thrown (distributed) as evenly as possible. This is the Uniformity of a sprinkler system. In its most simplified form, the more uniform a sprinkler system is in its coverage of the yard with water, the less water you have to put down on your yard to water it evenly. Efficiency is just a percentage form of the Uniformity of the sprinkler system. To determine how uniform a sprinkler system is, we perform an audit on the system by placing catch cans all over the yard and turning on the sprinkler for a set length of time and then taking reading of all for the catch cans and doing some statistical analysis on those readings to come up with the Efficiency.

After performing these audits we looked at the numbers and some of them were encouraging, sprinkler systems that we installed were better overall than those we did not install. We saw efficiencies ranging from 19% on the low side to 65% on the high side. The differences we saw depended on the brands of sprinkler heads used, how the heads were spaced and what pressures the sprinkler systems operated at. At 19% a system is wasting over 50% of the water used on the lawn!

As the second part of our winter project we set about testing the major manufacturers sprinkler products at different pressures and spacings to try and determine exactly what is the most efficient design, layout and pressure that sprinkler systems should operate with. We found that the precipitation rates listed in a manufacturers catalog are for maximum distances achievable only in an indoor test facility and are wildly inaccurate for real world applications. The operating pressure of a sprinkler zone can change the efficiency as much as 24% all other variables being equal. Updated nozzle designs by the same manufacturer at the same pressure, nozzle flow and spacing, can have as much as a 22% difference in the uniformity of a sprinkler zone.

Efficiency is not the only thing that affects how much water your sprinkler system needs to distribute on your lawn. Areas of direct sun and full shade should be zoned separate from each other so that the proper amount of water can be placed on these differing micro-climates. Trees or slopes can also affect how the system operates as do soil type, compaction and soil fertility. But if your sprinkler system is operating efficiently, it will be easier to handle those other issues within the environment.

Just as there have been incredible improvements in the efficiency of light bulbs, windows, furnaces and air conditioning systems, sprinkler systems components and designs are beginning to show those same efficiency gains. A lot of changes in the last 5 years have dramatically improved overall performance of the system components and as we as contractors polish our design methods we can make sprinkler systems more and more efficient. With an audit of your sprinkler system we can tell you exactly how your system is performing, what can be done to make it better and provide you with the exact time required to put down a specific amount of water on your lawn. Even a few improvements to your sprinkler system can make a significant impact on your watering costs. Let us come out and evaluate your sprinkler system. We can show you what all can be done to make your current system more efficient and how much water and money we can save you.