Water is arguably the most essential item in your bug out bag. At minimum, everyone should have one liter, per day, in their bag. In addition to water, consider packing a , which can filter out most bacteria from water sources such as lakes and ponds.
Clothing for your bug out bag should be chosen with the climate in mind. Two changes of clothes will ensure you always having something dry to wear. A rain poncho and gloves are good items to consider as they don’t take up much room.