Article: The schematic should include the main area you’d like to water and any adjacent areas you'd like to have covered by the sprinklers. Starting with a schematic will enable you to plan the routing of pipelines and placement of sprinkler heads so you can purchase your materials. Drawing out the area you'd like to irrigate will also ensure that the entire area is covered by the sprinklers. These will be your “zones,” or areas which will be watered as a unit. Consider the type(s) of terrain contained in each zone. For the sake of sprinkler installation, try to limit each zone to 1 type of terrain. For example, 1 zone could be a large, grassy backyard and another could include a garden or sidewalk-side shrubberies. Areas larger than 1,200 square feet (110 m2) would require special heads and a higher volume of water than you can normally get from a residential water system. Locate the sprinkler heads throughout the areas you’re watering in accordance with the spraying distance of the heads you chose. Mark the to-scale distance that each head will spray onto your schematic. Then, decide which shape you want each head to spray in.  A good-quality rotor head will spray an arc, semicircle, or full circle about 25–30 feet (7.6–9.1 m) in diameter. If you’re using rotor heads, situate each head about 45 feet (14 m) apart to allow adequate overlap.  Fixed pop-up head sprinklers spray roughly 10 feet (3.0 m). To ensure adequate coverage, install fixed pop-up heads about 18 feet (5.5 m) apart from one another. If you’re installing bubbler sprinkler heads, map them out so that the heads are located about 1.5 feet (0.46 m) apart, since each will cover a radius of roughly 1.75 feet (0.53 m).  As a rule of thumb, it’s better to have too much overlap than not enough. Keep in mind when you're positioning the sprinkler heads that the angle of spray on rotor and pop-up heads can be adjusted. Start the line from the location where you plan to install your control valves, timer (if automatically operated), and backflow preventer. Regardless of where you’re installing the water system, the main line will most likely start from an outdoor water nozzle.  Keep in mind that the PVC pipe you’ll use for the water lines can curve only slightly, so all lines must be straight and should turn at 90-degree angles. This portion of the diagram will give you an idea of the length of pipe you’ll need. The sketch can be rough, though. Branch lines are the smaller pipes that connect the main line to each of the individual sprinkler heads. Sprinkler heads themselves are never attached to the main lines, but always to the branch lines. You can route a branch line to more than 1 head if you use a 3⁄4 inch (1.9 cm) pipe, but 2 heads should be the limit. Further down the line, you may decrease the size of the main to 3⁄4 inch (1.9 cm), also, since near the end it will be supplying only 2 or 3 heads.
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Draw a roughly to-scale diagram of the areas you wish to irrigate. Divide the areas into rectangles of about 1,200 sq ft (110 m2) each. Mark the location of each sprinkler head on your diagram. Draw in the main water line. Draw branch lines from the main line to each head.