How Landscape Irrigation Works


Irrigation through a young garden.
Wally Eberhart/Visuals Unlimited/Getty Images
Irrigation through a young garden.

­Are you tired of lugging multiple hoses around your yard to keep grass, flowers and shrubs green? Perhaps you've noticed that many of your neighbors have installed irrigation systems. Did you know that using these systems can provide a substantial savings in water usage? Saving water and time sounds great, but what if you're also worried about saving money? With some knowledge and patience, you could tackle installing an irrigation system on your own.

In this article, you'll learn abo­ut the techniques of landscape irrigation, basic irrigation designs and how pumps and sprinklers work. For those of you who are really serious, you'll also learn about what you need to do to be professionally certified as a landscape irrigator.

One note of caution -- if you live in the Southwest or another dry region, check local laws to determine whether you can install a lawn irrigation system. In regions that are prone to drought or low precipitation, using gray-water after taking showers or doing laundry may be your best option. Xeriscaping, or landscaping for dry areas, is a fast-growing technique for areas that seldom get rain. Planting cacti and other desert plants can help to solve the problem of low water supplies [source: LandscapeNetwork.com].

More Landscaping

If you'd like to learn more about the history of irrigation, you may want to visit King City, California. King City is home to the History of Irrigation Museum, which i­s part of the complex at the Monterey County Agricultural and Rural Life Museum. The museum is dedicate­d to the history of irrigation in California, beginning with the early Spanish missions.

Not everyone uses the same kind of sprinkler system. Which one is best? Read on for some not-so-watered-down tips.

Landscape Irrigation Techniques

There are four major types of landscape irrigation. To determine which system is most suitable for your needs, you will need to consider the size of the area, the type of grass or plants you're irrigating, and whether you can live with the drawbacks of each system. The table below reviews and summarizes the advantages and disadvantages of each system type.

Type

Description

Pros

Cons

Micro-irrigation

Gives water directly to plants' root systems, using only as much water as needed.

Best for dwarf fruit trees, shrubs, groundcover; it's not a good option for lawns or turf.

Tubing can be damaged easily by dirt, freezing or vandalism because it remains above the ground.

Flood System

Floods the ground rather than spraying plants. Comes as jet system, bed sprayer, or bubbler.

Some plants -- ground covers, fruit trees, and roses, for example -- are prone to mold and disease from overwatering, which can result from other systems. Ideal for adobe or clay soil.

Often requires abundant water, and land must be flat so that water flows evenly and does not run off, wasting water and causing erosion.

Rotary Sprinkler

Spray head that rotates in a circle.

Can cover as many as 100 feet (30.5 m) from sprayer, which is ideal for turf or landscape.

Needs higher water pressure to function best. Rotating head may stick; requires checking as part of regular maintenance.

Spray Irrigation System

Traditional sprinkler head is most common form. Pop-up heads come up only when in use, which helps to prevent accidents.

Adjustable, covering from one to 15 feet (4.6 m). Works best in smaller areas that are regularly shaped. Performs well even with low pressure.

Sprinkler heads need to be replaced if water is full of minerals.

Not precise, so can waste a lot of water.

[source: LandscapeNetwork.com]

Feeling creative? The first step in landscape irrigation is designing the system. Read on to get your feet wet.

Landscape Irrigation Design

A Most Capable Man and Building a Better Pop-up

During the eighteenth century in Britain, the man you might have wanted to hire to plan your garden was Lancelot Brown, also known as “Capability Brown.” Brown made sure that the landscapes appeared to be natural and unplanned, even studying architecture to be sure his designs conveyed the classical idea of unity. One of his greatest works was Blenheim Palace, where British Prime Minister Sir Winston Churchill was born. Not bad for a man who began his career as a gardener's boy [source: Encyclopedia Britannica].

Once upon a time, spray heads didn't effectively water the area closest to the sprinkler, leaving brown circles on green lawns. Newer pop-up spray heads come with nozzles that have undercut sprays, a second opening beneath the main nozzle. This feature mitigates the problem of those unattractive brown patches [source: Tucker].

You're going to want to use graph paper to plan out your space. Figure out a system that will work for you, such as one square equals one foot. Draw your landscape on the graph paper. It's usually a good idea to use a pencil for your drawing, in case you change your mind.

You have two major choices when designing a landscape irrigation plan. If you have clearly defined geometric spaces (most lawns are squares or rectangles), you'll likely choose rectangular spacing. For purposes of irrigation design, sidewalks or driveways are irrelevant. The sprinklers will sit along the perimeters and in the corners, as well as any place where the imaginary grid lines intersect [source: Roberts].

Let's say, however, that you're dealing with an irregular-shaped lawn. A plan that uses triangular spacing will work best. Rather than marking off square grids, your design should be based on equilateral -- all sides are the same length -- triangles. This method generally offers better coverage than rectangular spacing does, even though there's likely to be at least one sprinkler that sends water farther out than you need. Figure the distance between the rows of sprinklers by multiplying the distance between sprinklers by .866 [source: Roberts].

How far apart the rows are is determined by the rating of the sprinkler head. You're aiming for coverage that goes from sprinkler head to sprinkler head. Don't worry, some overlap isn't bad. If the system you're looking at says it will throw water at a radius of 30 feet, take that with a grain of salt. These sprinkler heads are tested in prime conditions. If you live in a windy area, for example, that wind is going to blow the water and affect coverage.

Congratulations! Now you finally understand how your high school geometry class fits into the real world. Now it's time to check out pumps and sprinkler heads.

Landscape Irrigation Pumps and Sprinklers

Words to Ponder
Conserving water is green and has been for more than a century. In an address to Congress in 1907, President Theodore Roosevelt cautioned, "To waste, to destroy our natural resources, to skin and exhaust the land instead of using it so as to increase its usefulness, will result in undermining in the days of our children the very prosperity which we ought by right to hand down to them amplified and developed" [source: Mcdilda].

The power is in the pump! A less than optimal pump means less than optimal pressure to the sprinkler head, resulting in anemic water flow. Choosing the best pump is critical. When you're looking at pumps, consider one of two types: positive displacement pumps or Roto dynamic pumps. Positive displacement pumps are low-volume pumps. Within the pump, a displacer moves into the cylinder, allowing the water to enter and leave through sprinkler valves.

Roto dynamic pumps give energy to moving water through a rotating impeller. The system may use a turbine pump, an electro-submersible pump, or a jet sprinkler.

Sprinkler heads also come in two major types: rotors and spray heads. If you've seen rotating streams of water on a lawn, you know about rotors. Older, impact rotors tend to be distinctive for the noise they make, though newer rotors are gear-driven, smaller and quieter. Fixed spray heads work like a shower nozzle, sending out a fan-shaped spray.

When selecting a sprinkler head, consider the size of the area that needs to be watered. Spray heads are the better option for most yards. Rotors cost more per sprinkler, so even though they are spaced at greater distances than spray heads, they aren't economical. Generally, choose a pop-up head of at least three inches (7.62 cm) for the sake of both appearance and safety [source: Stryker].

Position sprinklers according to zones. Take into account both physical features and sun exposure.

Suppose you've had both great fun and success with your landscape irrigation plans. Friends, neighbors and family members are asking you for help. Is it time to make this a profitable hobby, or even a new career? Move on to the next page to learn about becoming certified in landscape irrigation.

Landscape Irrigation Certification

Becoming certified in landscape irrigation is gaining a professional credential that allows consumers to have confidence in your skill. It isn't required by law, but it's a good idea if you're serious about pursuing landscape irrigation as a career or a side job.

The first step is deciding what level of certification you want or need. There are three levels:

  • CID: Certified Irrigation Designer
  • CIC: Certified Irrigation Contractor
  • Certified Water Conservation Manager - Landscape (CWCM-L) [source: Irrigation Association]

International Irrigation Show
For more than you could ever imagine on the topic of landscape, turf or golf irrigation, consider a vacation that includes the International Irrigation Show. Each year during late fall, more than 350 exhibitors set up shop. In addition, the show offers technical sessions, a new product competition, and opportunities to network and attend seminars, education courses and exams [source: Irrigation Association].

Additional certification is available if you decide that your passion is for irrigating golf courses or becoming an auditor for landscape irrigation. Most of these positions require self-study or classes and passing a written exam. Between one and three years of experience or education is required before applying to take the exam. Classes are available for a fee from professional places like the Irrigation Association.

Registration for an exam must be done at least 30 days prior to the exam. Exams are given at trade shows regionally. Generally, it takes about a month to receive your exam results, but don't stress too much. You have three chances to pass before you must wait two years to begin the process again [source: Irrigation Association].

Certification must be renewed each year. A fee and a minimum of 10 Continuing Education Units (CEUs) are required to renew your certification. If going back to school makes you break out in a sweat, you can earn CEUs in other ways, such as by attending meetings, field days or trade shows. Seminars on the green industry or irrigation can also fill the requirement.

In addition to becoming certified, you may need to be licensed. Some states require you to pass licensing exams, often through a state bureau, such as a Department of Agriculture or Environment.

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