What always amazes me is the amount of gear folks DON'T carry on a hike. I have seen many show up with a ballcap, a water bottle, shorts and a light windbreaker on a fall hike at 4000ft elevation. If they ever had an emergency, they would be depending entirely on other party members to bail them out!
Myself, I carry more than the average (based on the underequipped people). I include a poncho, knife, a PSK with about 10oz of gear in it, small FAK, dry socks, extra clothing, a headlamp with spare batteries and lots of water! I have a widebrim hat, quickdry clothing and navigation equipment, always including a map and compass, sometimes a GPS. One item I also take on any desert hike is a 3ft length of silicone tubing. Good for sipping water from tiny pools in an emergency. I have built solar stills, even primed one with an entire barrel cactus and added a gallon of water to the pit, just to demonstrate how ineffective they are aroundd the arid SW. After 8 hours in the sun, the cup help 4oz of water! That was after adding a gallon to the pit!! Not very effective. Great effort goes into the solar stills construction too! A transpiration bag system is far more effective with almost no effort to get together.