If you're a backpacker you need a reliable yet lightweight method for purifying and filtering water in the wild. Most commercial methods are either bulky and heavy or need supplies such as salt and/or batteries. Instead you can make a gravity water filtration system using two water bladders, a $17 Aquamira Frontier Pro filter or likewise, and a pack of chlorine dioxide purification tablets.
If you're a backpacker you need a reliable yet lightweight method for purifying and filtering water in the wild. Most commercial methods are either bulky and heavy or need supplies such as YouTube user and veteran backpacker Jason Klass demonstrates the light weight, versatility, and low cost (around $40 for everything) of this setup. Basically you fill your "dirty" water bottle directly from a river, lake, or stream, add a purification tablet, and connect your clean water bottle to the Aquamira filter. The other side of the filter is connected to the water resevoir you drink from. Hang the dirty water from a tree branch and keep the clean water on the ground and in half an hour you'll have a couple of liters of clean water to drink.
Why does this system use both a chemical and a mechanical filter? The aquamira filter is good at keeping out dirt and objects that would change the taste of your water but does not filter closely enough to remove most bacterias and viruses. A chlorine dioxide chemical treatment (same as what most municipal water supplies use) will kill 99.999% of all viruses and bacterias and shouldn't change the taste of the water. If you run out of purification tablets while on the trail you can always gravity filter the water into a pot and boil it.
Ultralight Gravity Pro Water Filter | YouTube via Brian's Backpacking Blog
If you're hiking or exploring the wilds and you lose or bust your compass you can make a rudimentary compass by floating a magnetized needle. Instead of looking for a pond or puddle to hold your needle you can pour water into a ziplock bag to provide a stable surface for your needle to point north. 
If you ever have an emergency while out in the wild an effective way of getting help is to start a signal fire. You can make a fire with white or black smoke depending on your fuel source; choose whichever color provides the most contrast; Natural vegetation will produce white smoke and petroleum products produce black smoke. 
