There is no magic number. There are variables; plant and moisture requirements, planting medium, humidity.

What are you planting and your planned layout? North-south orientation?

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You should learn how to "read" your plants. They'll let you know when they're thirsty.

At the least, just stick your finger in the soil. It ought to be moist an inch or two down.

garden is south facing, my drip emitter is 0.50 gpm per emitter

I planting zucchini, beans, okra. I read somewhere that 1 inch of water per week is the standard (or 624 gallons per 1000 sf) but I'm afraid it won't apply here in Phoenix

Watering by numbers isn't smart.

When I do zucchini or any type of squash in the summer, I always cover the whole plant with a row cover (usually propped up with U shaped pvc) to retain moisture on the ground, keep certain bugs off them, and keep them from frying from the afternoon sun. You won't have to water as much and the plants are so much healthier. When it's hot out with no rain, I usually have to water at least once every 3 days, but it mainly depends on your soil. If it's loose soil that drains fast, you'll have to water more frequently.

Here in Fresno's summer heat.... 100 +++ everyday, I water daily. I've even found it helps to put a loose lattice work over the plants in the high sun of summer.... or they fry. We have very dry air here so tranpiration is a big difference here; I seem to remember Phoenix being humid from the summer monsoons, so you may have other factors than I.

Have you found your local County Extension Service? They can be very helpful with local gardening problems.

thank you everyone.