Hiking equipment
According to Tom Brown, the basic plan for survival is in the order of shelter (including clothing), water, fire, and food. Cody Lundin writes about the "Rule of 3s"; this relates to human survival without basics: three minutes without air, three hours without shelter, three days without water, or three weeks without food.
LifeStraw
The LifeStraw is a water filter designed to be used by one person to filter water for drinking. It filters a maximum of 4000 litres of water, enough for one person for three years. It removes almost all of waterborne bacteria and parasites. In addition to the classic LifeStraw, the manufacturer also produces other styles on the LifeStraw product: the LifeStraw Family, a larger unit designed for family use, and the LifeStraw Go Water Bottle, which incorporates a LifeStraw filter into a plastic sports water bottle.