What could be simpler? A bag with a trillion items surrounding it; just throw everything in and go trekking. Mountains, skies, freedom. A few days later it becomes clear most of the items were not necessary, and that the extra towel left behind was essential. Moreover, your back is in pain because the items were distributed in the wrong way. Bag packing is an unusual form of art, but it is one nonetheless.
I do recommend splitting the equipment in two backpacks. The big one should be carried on the back and would contain items not needed on a short notice. The second should be small and contain items that may be needed in a hurry. The best is if the small one can be attached to the bigger one or carried on the chest, allowing the trekker more flexibility.
What to Take
The list of items to take for a trek is tricky. It depends on its length, path and season; each one of these parameters defines different needs. Yet, some items and principles are common to all options.
A sleeping bag is one of the most important items, especially during the last days of the trip when the temperatures drop quickly. The beds provided by most guesthouses along the way are rather basic and not suited for cold weather. A convenient solution is to reach Namche Bazaar without a sleeping bag and to rent one there before climbing any higher.
A thin fleece is another very important item, it would provide a very important protection from the weather once the 4000m line is crossed and yet it is light and can be fold really small. A related item is a waterproof and windproof jacket. Its lack of inner insulating layers is important; the trekker would generate enough heat while walking. Moreover, the smaller it folds the better. Both items can be purchased in Thamel (see that entry).
Take enough clothes to change in the case of a disaster (like getting wet to the bone, or slipping on a muddy surface) but neither too much nor too fancy. Nobody expects a trekker to dress up for a high tea at a Nepali teahouse or a gala dinner at the nearest village.
A well-insulated, one liter plastic bottle and iodine tablets are essential. The last can be purchased at KEEP (see that entry). An insulating sleeve that allows attaching the bottle to the small backpack is recommended.
Maps, guides and compass should all go in the small backpack. The same goes for a small knife, spoon and torch; basic sanitary items are a must. LED based torches are more energy efficient and thus better suited for a long trek in isolated areas. Paper items should be protected so that they don’t get wet. The best is to find a small backpack with pockets near – or in – its bottom and to wrap the items with plastic in such a way that they can be easily retrieved.
Sunglasses, sun hat and a protecting hat for cold weather are essential. Make sure the sunglasses are fit for a high solar radiation environment.
How to Bag Pack
The order in which certain items are put in the backpack is important, even crucial. Heavy items should be placed as low as possible in the big backpack. otherwise this would cause back pains and instability while walking on difficult terrain. What are heavy items? Few people realize this, but paper is relatively dense when compared with other items a trekker carries. Books should be put first and at the very bottom of the backpack.
A real problem is how to deal with a rainy path. The event would occur almost for certain, and the trekker must be ready to deal with a couple of hours under the rain until a shelter is reached. Most important is to have plastic protectors for the backpacks. If they came without covers, those can be easily purchased in Thamel. Second, walking with rain dropping on the head is unpleasant, at least after a while. Carrying an umbrella is on the verge of ridiculous and extremely uncomfortable because the shoulders are strained under the backpacks. Covering oneself with a plastic sheet is a big error; the micro-climate created within the plastic would nearly cook the trekker. The best solution I found is covering the head - but not the face - with an extra towel carried especially for that purpose around the neck.
Laundry is a problem. If arriving to the village where the night is spent after dark, then doing laundry and expecting to leave the next morning with dry clothes is unreal. The solution is to carry enough clothes for a few days of walking and then doing laundry at the villages where an altitude acclimatization stopover is taken. Another point strengthening this recommendation is that in all the popular stopovers there are laundry services offered. See the Altitude Trekking entry in my Everest journal for details on these stops.
What are all those straps on the big backpack for? Depending on the model, the backpacks would feature an array of straps at sometimes strange places. Get acquainted with their use. The point is to get the backpack attached as tightly as possible to the body so that it doesn't move while walking. If it moves it would unbalance the trekker and may even cause accidents. These types of activities are what evenings at a guesthouse in the mountains were made for.