Young citrus trees require water at least once a week and more mature trees should be watered about every two to four weeks. Adjust for wetter or dryer weather.
Citrus trees doesnt need much watering, twice or thrice in a week is more than enough for them in California.Nourishing them with some fertilizers would be a very good thing.
Citrus trees should be planted such that they have good drainage, and should be watered relatively often. The trees themselves should not have soil that is flooded, but instead moist to the touch.