Irrigation Systems

Yard and Lawn Irrigation Systems

If you plan on maintaining a sizable lawn and want to keep it green during the growing season, a permanent in-ground irrigation system can conserve water and save time, too. A properly installed system can deliver just the right amount of water when and where your lawn needs it, and it eliminates the need to drag portable sprinklers and hoses all over the yard. In-ground sprinkler systems also make sense for a vacation home that you visit irregularly or if you travel frequently and are not always home in summer to attend to your lawn's water needs.

How Permanent Sprinkler Systems Work

A typical in-ground sprinkler system delivers water via a network of underground pipes to all areas of a lawn. It consists of multiple control valves, each of which can either stop or start the flow of water to an area of lawn, or zone. Each zone consists of several sprinkler heads attached to buried pipes by risers (short vertical pipes) that are arranged to provide uniform water coverage to the grass in that area. Systems are divided into zones because household water pressure is capable of supplying only a limited number of sprinklers at one time.

There are two types of in-ground irrigation systems, manual and automatic. A fully automated in-ground system will typically include a programmable controller that allows you to schedule when and where various portions of your lawn will be watered. A signal from the controller activates a small servo-motor that opens or closes each control valve at the programmed time. Some automatic systems, such as Toro's, are equipped with moisture sensors (weather or soil) that override the controller program and prevent the system from turning on during rainy weather or after rain, while the soil remains moist. A manual system requires that you turn the control valves on and off by hand.

There are several types of lawn sprinkler heads, including sprayers that deliver a fine, mist-like spray and rotary heads that throw water in a wide circle, much like a portable rotary sprinkler does. Spray-type heads are specified for systems when accuracy of coverage is critical. Rotary heads deliver water to larger areas, so fewer are required. Pop-up varieties of each type of sprinkler head, spray and rotary, rise several inches above grade level when water pressure is introduced. This ensures that groundcovers and low shrubs don't interfere with water delivery.

Sprinkler heads are installed in either triangular or square grid layouts. Make sure that the spray from one sprinkler head reaches the next one, for head-to-head coverage. This allows even coverage. Without overlap, the grass farthest from the sprinkler heads would receive less water than the grass near the heads, whereas some spaces between the sprinklers might not receive any water at all. Many sprinkler heads can be adjusted to control the amount of water delivered. They can also be adjusted to deliver water in a variety of patterns. A full head delivers water in a full circular pattern. The other circular patterns are half, quarter, and adjustable. Adjustable heads can water any part of a circle, from 0 to about 330 degrees. There are also rectangular and square patterns for narrow rectangles of turf or perfectly square areas, and there are end, centre, and side-strip patterns for grassy pathways, side yards, and other tight spaces.

Assessing Your System.

A well-designed sprinkler system will deliver water evenly to all grass areas. It's important to select heads that provide the right spray pattern for your needs but that also avoid overspray onto streets, paths, driveways, patios, buildings, and unwary passers by. Also, avoid placing a sprinkler where it will spray directly onto the trunks of trees and thereby damage the bark. The sheer force of the water pressure can score the bark, and constant wetting weakens it, making it more susceptible to pests and diseases. Misdirected spray can also blast the petals off flowers. If you suspect uneven coverage--several parts of your lawn tend to be dry and brown, for example--try a simple test to be sure your sprinkler system is to blame.

Place a half dozen containers, such as tuna cans, throughout the affected area and run your system. Note the depth of water collected in each can and calculate an average depth. Perform the same test in areas that seem to receive adequate water (preferably at the same time of day to avoid variations due to fluctuations in water pressure), and make your comparison. If one area is receiving 3/4 inch of water in an hour and another is only getting 1/4 inch, make adjustments. Otherwise you will have to choose between two evils: continuing to deliver inadequate water to some areas and risking brown patches, or using more water than necessary elsewhere to ensure adequate coverage to areas with an inadequate rate of delivery.

If you don't own an in-ground automated sprinkler system and feel you need one, it is a relatively easy job for an accomplished do-it-yourself homeowner. Installing and in-ground lawn sprinkling system is a job that requires careful planning, considerable wiring, lots of excavation. Errors in design or execution will be costly to fix.