Energy bar wrapper If it’s metallic-lined, you can flash a signal and catch the attention of rescuers from as far away as 1.5 miles, according to testing by Ted Alvarez, BACKPACKER’s survival-gear guinea pig. “Just polish it with a little spit, and flap it around like crazy in the sunlight,” he says.
Can or bottle Boiling is a foolproof way to purify even the mankiest water source. Cut the top off a discarded can, fill it with water, and bring to a boil on a fire. You can even boil water in a plastic bottle (above) as long as it’s suspended a few inches above the flame (a tripod of green sticks works well). The water will come to a boil before the bottle melts. Just remove the cap to prevent pressure buildup, which could result in a burn when you uncap it. Be patient, as it can take up to 10 minutes for a quart. For best results, keep the bottle swinging gently over the flame.
Plastic sheeting or bag Create a solar still for gathering water. Cut the plastic into two large pieces (black bags work best because they absorb more solar energy, but any plastic will do). Dig a hole two feet deep and line it with one sheet of plastic. Pee into the plastic, then set an upright container (a cup fashioned out of a can or water bottle) in the center of the hole. Add fresh green foliage if available. Cover the entire depression with the second sheet of plastic and weight it in the center over the container. As the pee evaporates, potable water will condense on the upper plastic and drip into the cup.
Garbage bag Climb into a large plastic sack and fill it with insulation: leaves, grasses, dry moss, and duff. Backfill around your body to trap heat on all sides. You can also use this technique to make an insulated mattress.
Plastic grocery sack In frigid conditions, create vapor barrier liners inside your boots to trap heat. Just place a bag over each foot, then put your socks and shoes on. The plastic, while it may not feel good next to your skin, prevents body heat from escaping.