I have just spent some time working through my 1 day pack contents
35 litre Backpack
First Aid Kit (as posted yesterday)
Hat
Sunglasses
2 Neck tube type Bandannas
Dry Sack (for clothing etc.)
Medication (Ibuprofen, No-Doz, Ventolin) in waterproof bag
Fire Kit (Matches and cotton-balls coated in Vaseline) packed in waterproof bag
Water for one day, canteen in insulated pouch, can be carried over the shoulder instead of in pack, or attached to belt with alice clips
Insect repellent
Binoculars
Compass
Parracord bracelet with whistle and ferro rod
Parracord pocket knife with carabiner to attach to belt
Travel Towel
Poncho with eyelets so it can be used as an emergency shelter
Garbage bags (lots of uses in an emergency)
Still Missing
Water filter (life straw)
Water purification tablets.
metal cup (billy)
Emergency Bivy bag
Multi-took with pliers
For overnight hiking
I have some basic light weight cookware but I still need a new sleeping bag as mine is to bulky and heavy, an ultralight tent and a trangia stove.
I also should get a PLB. I also have a larger hiking pack but it is looking a bit rough and has some damage so is also on the list to be replaced. Maps added to bag as needed.
Added to all of this is clothing and food. I also have a small pouch which can be added in an emergency with a USB of important documents photographs, and photocopies of documents in case of an emergency evacuation (Cyclone, Fire etc.) turning my hiking gear into a bug out bag for the family.