It’s important to choose the right irrigation system for your home, not only to save you money and conserve water, but to ensure your yard and plants will flourish. Many factors are taken into account before installing a system, such as the types of plants in your landscape, wind exposure, soil type, and your water pressure. Many homeowners will use a combination of different irrigation types.
Turf rotor sprinklers operate by rotating single or multiple streams of water back and forth. Most people are familiar with the “impact” rotor sprinklers that make a distinct sound as they move and shoot out bursts of water.
Impact rotor sprinkler specifications:
- Arc rotation: 40 to 360 degrees.
- Radius: 20 to 150 feet.
- Water pressure: 25 to 50 psi (pounds per square inch).
- Precipitation rate: 0.1 to 1.5 inches per hour.
Impact rotors are best for large garden beds, and large commercial and residential properties. These rotors are being replaced now by gear driven rotors that are very quiet, and much smaller.
Gear-driven rotors are one of the most commonly used sprinkler heads for small commercial sites, athletic fields, and large residential areas, because of their low cost, various spray patterns, and quite operation.
Their enclosed body design prevents dirt and debris from clogging the drive mechanism. They’re a better choice than pop-up spray heads in areas with clay or slopes because their lower precipitation rate increases water absorption.
Gear-driven rotors use nozzles, and manufacturers often provide a nozzle tree with their rotors, giving a choice of radius and precipitation rate. They’re also available in different pop-up heights (e.g. 2 to 12 inches).
Gear-driven rotor specifications:
- Arc rotation: 40 to 360 degrees.
- Radius: 18 to 55 feet.
- Water pressure: 25 to 75 psi (pounds per square inch).
- Precipitation rates: 0.2 to 0.8 inches per hour, depending on the pressure, nozzle size, and zone layout.
Rotary nozzles, or rotator nozzles, are a new type of miniature rotors introduced in recent years. The first brand on the market was called the “MP Rotator”, and similar products quickly became available from other companies. Many manufacturers classify them as “spray heads”. They’re called rotary nozzles because they’re the same size as the standard nozzle in a spray-type sprinkler. This allows them to fit onto the smaller and less expensive spray head pop-up bodies. They’re considered more efficient than spray heads because they don’t produce as much “mist” or “fog”, and more water reaches the ground. They can also reduce water usage up to 30 percent by reducing water runoff with their lower precipitation rates, and providing a greater radius of coverage and uniformity of distribution.
All rotary nozzle models deliver multiple, individually distinct streams of water that rotate around the nozzle (they look like rotating spider legs). Most have adjustable radii and arcs, with some being hand-adjustable. They’re used for smaller and intermediate sized areas, irregularly shaped properties, and narrow strips. As well, retrofitting with rotary nozzles allows older irrigation systems to run at a lower pressure, getting more coverage at the same time, and equalizing pressure among all zones.
Rotary nozzle specifications:
- Arc rotation: 45 to 360 degrees.
- Radius: 15 to 35 feet.
- Water pressure: 20 to 55 psi.
- Precipitation rate: 0.4 to 0.8 inches per hour.
Shrub-style rotary sprinklers are an option when you need to water over the top of tall, dense shrubs. These sprinklers are designed to be installed above ground on top of a very tall pipe, or riser. It’s best to use them, however, when nothing else will work — many people are injured each year when they trip over them. If no other irrigation solution is available, use shrub-style sprinklers well away from patios, sidewalks, and children’s play areas. Make them clearly visible by strapping them to a wood or plastic fence post.
In Texas, drought concerns and “watering windows” that reduce irrigation times mean watering efficiency is of the utmost importance. Matched precipitation rates are mandated by law, and matched precipitation rate (MPR) rotary nozzles help meet the challenge of restricted watering times. MPR rotary nozzles produce a uniform amount of water across each square foot of irrigated area, regardless of their spray arc. A head with a half circle arc will deliver just as much water per square foot as a full-circle head spraying the same distance. MPR rotary nozzles allow sprinklers with various arcs to be mixed in the same zone, while maintaining even water distribution rates.
For irrigating larger areas, MPR nozzles are also available for gear-driven rotors.
Spray heads, or “fixed spray heads”, are small sprinkler nozzles that pop up to spray a fan-shaped water pattern and recede into the ground when finished. They use interchangeable nozzles to change their pattern (1/4 circle, 1/2 circle, full circle) and the radius of the water throw to fit the shape of the landscape. For long, narrow areas, some specialty patterns are available.
Most manufacturers produce spray heads that allow you to mix and match nozzle patterns, so you’ll still have matched precipitation rates. Make sure you’re not mixing different brands of spray heads and nozzles together in the same zone without checking to see if they have the same performance specifications.
Spray head sprinklers spray high volumes of water in short periods of time.
Spray head sprinkler specifications:
- Arc: 0 to 360 degrees
- Radius: 5 to 18 feet.
- Water pressure: 20 to 30 psi.
- Precipitation rate: 1 to 2.5 inches per hour, depending on system pressure, spray head spacing, and nozzle size.
Sprinkler head height is determined largely by soil type, soil condition, and other watering requirements. Pop-up sprinkler bodies are available from 2 to 20 inches in height. You’ll find 2-inch pop-ups in areas where hard soil makes digging difficult; 4-inch pop-ups are used in turf areas to provide enough clearance for a growing lawn and compensate for any settling due to soil and thatch build-up; 6- to 12-inch pop-ups for ground cover, gardens, and shrub borders; 12- to 20-inch pop-ups are used where more clearance is required to distribute the water effectively.
Generally, spray heads are used to irrigate small to intermediate flat-surface areas, and smaller, hard-to-reach lawn sections. Spray heads are also a good choice to use in areas where you want to avoid spraying cars, the street, and your house. They shouldn’t be used on slopes because their precipitation rate will create runoff.
Subsurface drip irrigation is a low-pressure irrigation system using underground parallel drip tubes that contain embedded emitters placed at regular intervals. The tubes are usually buried 4 to 6 inches deep, and the holes are designed so they won’t become clogged with soil or debris. Emitters and tubing are now available that prevent root intrusion without the maintenance or replacement of chemicals.
Subsurface irrigation is a good solution for groundcover and shrub areas, and lawns that are difficult to water, such as those with narrow strips of grass, unusual shapes, or steep slopes. It’s a highly efficient system — no water is lost to sun or wind evaporation. Lawns watered with this method don’t suffer from fungus diseases caused by over or underwatering.
Drip Irrigation is also known as trickle irrigation or localized irrigation. Like the subsurface drip irrigation, it is a low pressure irrigation type but, in this case, the water is released on top of the soil to target specific plants and their root zones. The rate of water flow can be set between 1 and 10 gallons per hour, making this type of irrigation customizable to different types of plants in your garden.
The next article will examine micro irrigation systems.
A licensed irrigator will know how to design, plan, and install any of the irrigation types and is uniquely qualified to advise you on the irrigation types you should use for your landscape.
For the best in irrigation design, installation, maintenance and repair, call Smart Earth Sprinklers at (512) 694-1147.