Planning an irrigation system

Irrigation system components

• The main sprinkler line to which the valves and valve manifolds will be connected.
• Header lines which will bring water to your landscape.
• Lateral pipes connected to the header lines which will feed the sprinkler heads.

• Controls the on/off flow of water to each watering “zone.”
• An assembly of several valves together is called a “manifold.”
• According to the number of zones in your system, you may need to install more than one valve manifold.
• Calculate one valve per irrigation zone.
• Connect the pipes of the main sprinkler line to the header lines.

Certain systems allow you to connect your valve manifold to the water outlet you use to attach your watering hose. This simplifies the installation but is only viable for small-scale use. Larger systems require new piping intended exclusively for the irrigation system installation.

• Connected in a straight line from the main shut off valve to the valves or manifolds.
• Usually includes two pipes from the main shut off valve to the front yard manifold and backyard manifold.
• Must be one size larger than the main water supply line for the house.
• If the main sprinkler line is ½", limit its total length to accommodate 150 to 200 gallons per minute.

• Attached directly to a zone manifold to supply water to the lateral lines.
• Intersected by lateral lines.
• Must be at least 1" in diameter.
• Sprinklers should not be installed on them directly.

• Used to connect each header line to individual sprinkler heads.
• Must be straight and branch off from the header line to supply water to the sprinkler heads.
• Must not be smaller than 3/4" in diameter.

• On your irrigation plan, place a sprinkler head in each corner. Then use a compass to draw the spraying pattern around each sprinkler head.
• Add sprinklers along the perimeters and in the center to increase coverage. Adjust spacing.
• Space the heads at regular intervals and overlap the spray-pattern diameters by 50% to ensure complete coverage.
• There should be no dry patches remaining.
• To irrigate narrow strips, use spray heads with strip nozzles. These nozzles typically water areas up to four feet wide.

The first step in planning your irrigation system is to measure your property.

• Note all measurements, including trees, shrubs, driveway, walkways, tool shed, patio, and all other obstacles.
• Make a scale drawing on graph paper so you have a top down view of your entire property.
• Label different areas of the yard, including the lawn, flower beds, container plants, trees, shrubs, and vegetable garden or rose garden if you have one. Each area will represent a different watering zone, with one sprinkler head per watering zone required.

• Designate watering zones based on soil conditions, plants to be watered and quantity of water required. Shaded areas of the property will have different needs than full-sun areas, just as certain plants require more water than others.
• Different types of sprinkler heads should not be used for the same zone: each individual zone will use only one type of sprinkler head.
• Determine the maximum water flow capacity for each watering zone to make sure the number of sprinkler heads per zone does not exceed this maximum. Manufacturers provide planning guides to help determine maximum water flow and the maximum number of sprinkler heads per zone.
• Individual zones may use different-sized pipes.
• Label each watering zone on your plan with the maximum allowable number of sprinkler heads. Include the suggested sprinkler head size (small, medium, large) on the plan.
• Assign numbers to each watering zone for easy reference.

• Determine the actual or approximate sizes of the pipes for the entire irrigation system.
• Draw a direct route for the main sprinkler line from the main shutoff valve or main water supply to the front and backyard manifolds.
• Draw header lines directly from the manifold to each zone.
• Draw lateral lines that connect each header line to the sprinkler heads.

• Determine a logical place for the system’s main shut-off valve. This valve will shut off water to the entire sprinkler system.
• Connect the main shut-off valve to the sprinkler valve manifolds.
• Put one manifold in the front yard and one in the back yard.
• Locate each manifold in an accessible area, away from heavy foot traffic. If possible, locate it on elevated ground to avoid water pooling around it.
• Clearly indicate the location of the backflow preventer on the drawing

• Place the timer close to an available power source where it is easily accessible.
• Install the timer in a weather-resistant box.
• Electrical wires will be needed to connect the timer to each manifold valve.
• Draw lines from the timer to the front and back yard manifolds as well as any additional manifolds required for an extended irrigation plan.