Water is key to being well in heat, for sure. I found this water filter option that looks quite light weight and very easy to use. Good for camping and for emergencies if there are natural sources of water nearby: http://www.rei.com/product/786393/sa...system-2-liter
. Only weighs a pound for the kit and packs away in a small space. Pretty darn light considering a gallon of water weighs about 8 lbs.