The best thing to do is to wake up before the sun, pack everything up, and get going at sunrise, near 6 o'clock. This lets you appreciate the cool morning air. It usually gets really hot as early as 9 o'clock. The hottest time of the day, around 2, should be dedicated to a siesta, unless you're in a real hurry. Water Water isn't always easy to find.
Most maps show springs, but they can be very hard to locate, or dry.
Carry a large flask. 1.5 liter sounds right. 1 liter should do but you might be in trouble if you don't find a spring before the evening. No special equipment is needed, just the usual mountain clothes. Remember that although the wheather is usually hot and clear, you might also experience a few violent storms.