When it comes to designing a sprinkler system, there a lot of things to consider. First the soil type. For example a sandy or loam soil will drain much more quickly than a clay type of soil. Then the climate is a big factor, in Dallas Texas the summers are very dry and the rainfall low, so that must be taken into account. For example around a house foundation, if the soil around the foundation dries out too much, it can put extreme stress on the house foundation, and they could possibly crack, so it is important to have some regular watering close to the walls of the house.
Other important design factors include the type of plants in the backyard. A large area of lawn will need more regular watering than a planting of hardy natural foliage, which may be adapted to use less water than grass. If there are paths going through the garden, these must be accounted for in the design, as you don’t want to be watering a concrete path, as the water will just run off and pool where you don’t want it to. Not to mention water loss due to evaporation over a large hot area of concrete. Also important are any major plants such as trees, which not only soak up a lot of water, but will also block the travel of water from sprinkler heads, both pop up and impact sprinklers.
One of the less obvious design variables is the amount of water pressure. If you are using city water, be aware that during summer watering restrictions many people will be watering their yards at the same time, and this may cause your water pressure to drop, which reduced the distance that a sprinkler head can reach.
So with these factors in mind, draw out the sprinkler design on graph paper, which is an easy way to see where the sprinkler heads need to be placed to best water the larger grassier areas, and avoid any obstacles such as trees or other fixed structures. Draw each sprinkler head with the chosen sprinkler pattern (these can be full, half or quarter circles, end strip or side strip spray patterns)on the paper to get an idea of where to position them. Ensure that each sprinkler head has an overlap with adjacent heads, both for best coverage, and also to account for water pressure drops.
Finally divide up the sprinkler heads into zones. Each sprinkler zone is typically controlled by an electric sprinkler valve, operated by a central controller. Then your sprinkler design is ready for laying out the underground sprinkler pipes.