Please don't plan on buying plastic throw away bottles to trash the land every day. Purification drops will work also but can get hard on your digestion after a while. You can find water purifiers at most hiking stores. You need two water containers, one to pump from and another to carry the purified water. A PUMP, they can be shared between 4 or so people.
Most people do fine, perhaps moving kind of slow, but all right.
We will have available homeopathic and other natural medicines and there are native Andean herbs that can help. Most of our journeys adjust by starting low, and moving slowly over several days to the highest places thus very few people are bothered by the altitudes. Traveling the Andes means everywhere we go takes walking up and down. The elderly and infirm have been able to make it, however slowly. In the knowing of holistic happiness, physical strength can add much to mental and spiritual growth.