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How Do Sprinkler System Zones Work?May 14th, 2013 by
Do you daydream of not having to drag heavy hoses across your lawn to keep your grass from turning brown in the summer heat? Does the thought of giving away your collection of moveable lawn sprinklers bring joy to your heart?
If you answered yes to both questions, you need an automated sprinkler system.
While irrigation systems are designed to be user friendly, their design can be complicated, so it’s best to leave that step to the professionals. And when the pros tell you that arranging your sprinkler system in zones will give you the best results, believe them!
Zones are the key to efficiently and effectively irrigating a lawn. Most yards include more than just grass, and these different areas have different water needs based on the variety of plants, topography, and level of shade and sun. This is where zones come in handy.
To direct water to different parts of the lawn in an exact, controlled way, an irrigation system designer should arrange the sprinkler heads—create zones, in other words—to provide good coverage. In addition, the entire system must be calculated to avoid exceeding your home’s water pressure and maximum flow rate.
Each zone can be further customized with different sprinkler heads to make sure your plants get exactly what they need when they need it.
Sound interesting? Keep reading to learn more.
Sprinkler Zones and Irrigation System Design
The primary advantage of dividing a sprinkler system into zones is the ability to fine-tune the water supply to each part of the landscape. As you work with an irrigation system professional, you’ll need to think carefully about the different parts of your lawn.
Zones for grassy areas
Grass vs. trees and shrubs: Most trees and shrubs require little more than Mother Nature provides, while grass benefits from regular irrigation. Check out our blog on the best grass watering tips to help you identify and research your particular type of grass and find out how much and how frequently you should water it.
Sloping areas vs. flat areas: Sloping areas must be watered with care to prevent excess runoff that can erode soil, flood your lawn, or wash away nutrients and fertilizers.
Shady areas vs. sunny areas: Shaded grass retains moisture and requires significantly less watering than grass that gets plenty of sunshine.
Each of these areas should be its own zone or, if the area is too large, a cluster of zones. Each zone will be supplied by its own valve, enabling you to irrigate the zones that need water while leaving others nice and dry.
Zones for flowers and vegetables
Keep in mind that flowers and vegetables won’t benefit from the heavy, wide spray of traditional sprinkler heads suited to many other zones. Drip irrigation is a far better setup because it delivers water directly to the roots of fruiting or flowering plants.
However, sprinkler heads and drip irrigation should not be mixed in the same zone, so if your landscape includes a garden of vegetables or flowers, give the garden its own zone and use drip irrigation lines.
Selecting and Plotting Your Sprinkler Heads
Analyzing your yard in terms of the location of trees, slopes, shade, grass, flowers, and more is half the work involved in getting your sprinkler system up and running. You’ll still need to select the right sprinkler heads for your yard.
Outfitting your zones with the right sprinkler heads requires precise technical measurements, like the dynamic water pressure and maximum available gallons per minute of your home’s water supply.
You can take rough measurements of both these values using a pressure gauge and a five-gallon bucket, but your sprinkler system will benefit from a professional level of precision.
An irrigation specialist knows how to measure water pressure and gallons per minute very accurately and can even account for changes in elevation as well as friction within your irrigation pipes.
How to plot sprinkler head location
In most cases, sprinkler heads (not including drip irrigation lines, of course) should be laid out in similar formations.
Sprinkler heads capable of delivering wide coverage will spray water in 360-, 180-, and 90-degree patterns—circles, half-circles, and quarter-circles—so, regardless of which kind you select, you’ll use the same principles to space them correctly throughout your zones.
There are many different styles of sprinkler system heads, and which ones you choose is primarily up to you. For additional information on selecting sprinkler heads, check out our overview of sprinkler system installation.
Once you’ve chosen your hardware, your irrigation system designer may mention the following layouts for the sprinkler heads:
Head-to-head coverage. Head-to-head coverage prevents dry spots. Because sprinkler heads distribute water in circular shapes rather than perfectly interlocking rectangles, plotting them so that the edge of each spray radius barely grazes the others will leave patches of your yard without water.
Imagine three pennies in a tight triangle formation. If each penny represents an area sprayed by a sprinkler head, the empty spot at the center of the triangle would be an area of your lawn where none of the sprays reach.
To prevent these unwatered patches, make sure that the spray radius of each sprinkler overlaps significantly, reaching or nearly reaching the adjacent sprinkler head.
Rectangular or triangular patterns. Rectangular or triangular patterns deliver water most efficiently—that is, they achieve the most overlap with the least amount of water.
Rectangular patterns of sprinkler heads suit small- and medium-sized areas as well as corners and long, straight perimeters. Triangular patterns are very efficient in large, open zones, and they can also provide economical coverage for irregularly shaped borders.
The Bottom Line
Sprinkler systems make keeping your landscape healthy so much easier—no lugging around hoses or waking up before dawn to water the grass. Zones help optimize your system.
That bed of beautiful heirloom roses in your side yard has different watering requirements than the dogwood by the mailbox, after all, and well-designed irrigation zones will deliver the right amount of water to each location at the right time.
Designing a sprinkler system that functions as it should and meets the needs of your yard is not an easy task. Consult with a professional, and then sit back and enjoy as your landscape flourishes under the individualized attention of your irrigation system.