Once you have decided on sprinkler heads and have created zones, you can plan your sprinkler valve placement. First, you need to decide on a location for your main shut-off valve. The main shut-off sprinkler system valve will shut off the water for your entire lawn sprinkling system. You can connect to the main water supply downstream from your water meter. Be sure to mark the location of your shut-off valve on your graph.
Using your graph and zone locations, you can plan valve placement. There should be only one sprinkler valve per zone. You can group your sprinkler system valves all together using a valve manifold. It is quite common to install one manifold in the front yard and one sprinkler valve manifold in the backyard. They should be placed in an easily accessible location away from foot traffic. If possible, your valve manifolds should be placed on elevated ground so water does not pool around your sprinkler valves. Be sure to mark the locations of your valve manifolds on your graph.
Next, you will need to plan where you will place your backflow device. There are several different backflow prevention devices from which you can choose: pressure vacuum breaker (PVB), anti-siphon valve, dual check valve, etc. Decide on a location for your backflow device and mark it on your graph.
After you have planned out your valve placement, you can begin working on your pipe layout.