If you have a well pump, and you plan to irrigate your yard with an automated sprinkler system, your task becomes slightly more complicated than installing a sprinkler system in a home that gets its water from a municipal water supply. You have to consider the level of water in your aquifer, the size of your pumps, and the pressure you are able to achieve. Once you know these values, you can then get started on the task of designing your sprinkler system.
In some areas, it is possible to pump water out of your aquifer faster than the aquifer can fill up. If you are doing normal household tasks, this should not be a problem, but if you are going to be running a sprinkler system for an hour or more, you could deplete the aquifer. If the water level falls below the depth of your well, your pump could run dry, which can burn up the motor. Thus, you need to make sure that your well is deep enough that depleting the aquifer is not a concern. You may also have to cut back on watering times.
In general, the larger your pump is, the further it can push water and the larger the volume of water it can pump at a time. Both of these factors will affect how large you can build your system and how many sprinkler heads you can put on each zone. In order to limit cost, you want to put as many heads as possible on each zone because this will limit the number of sprinkler valves you have to buy. If you can't pump water to the far reaches of your property, you may not be able to have lawn to the edge of your property and will have to come up with another plan for landscaping the edges.
Sprinkler heads are designed to run in a certain range of pressure. You may need to adjust the pressure valve at your pressure tank to make sure that you are able to produce enough pressure to power your sprinkler heads. You also want to make sure that you are able to keep your pump on all or most of the time that your sprinklers are on so that it is not constantly cycling on and off.
If you are having a hard time figuring out aquifer level, pump size, and pressure settings, you should talk to the company that put in your pump and/or a sprinkler company to see if they can help with your well water system.