Datrex Emergency Water Packet - my husband and I each have a supply of these in our vehicle bug-out bags, along with a stainless steel water bottel. The bags that hold this water don't break down like plastic water bottles will do in your trunk.
Hanging Water Bag --Fill this bag from a nearby lake or stream and soon you'll have safe, bacteria-free, filtered water. The bottom of the bag contains 2 of our ceramic filters in a shockproof plastic cage, and if the bag is kept full, it can produce up to 10 gallons of filtered water per hour. The filters last a full year. If the end of the tube is placed in a container it will start a siphoning action, and the flow rate will be even faster. Great for your bug-out kit!