I know some places have outlawed it, but I use rain barrels. Hardly takes any rain (maybe .10") to fill up 100 gallons worth of barrels, and I rarely empty them before the next rain. Of course, I'm in Pennsylvania, not exactly an arid area.
In general though I always advocate for mulch, and then some more mulch. 3" is ideal. Keeps water in the soil, reduces water stealing weeds, and improves soil structure to promote water retention.