In the world of landscape irrigation there are several types of systems. Spray (Overhead) systems, drip, rainwater harvesting, laundry to landscape and soaker hose. With these options how do you know which is best for your landscape? The answer is simple.
If you have large planter beds then an overhead system is best as it mimics natural rainfall. In this video Hunter Industries explains their Pro-Spray product guide.
If you have small planter beds where an overhead system will not work well then I would suggest you consider a drip system. This video will explain your options.
Remember that each garden is different. Your unique situation will dictate exactly what type of system you have. How often you water will also depend on the type of plants that you have. If you are using California native/drought tolerant plants then you should be watering twice weekly for 10 minutes for the 6-8 months and then taper down as needed.
In regards to the rainwater harvesting and laundry to landscape option is also doable alongside of the the above two. You should just be careful if you are going to connect your gray water to your landscape that you do not connect it to your edible plants as the dirty water is not safe for ingesting. You cad read this post here to see my favorite rain tank.