There are other alternatives to water treatment. Distillation, filtration, reverse osmosis, and chemical purification.
These are a few that I have found and have considered in addition to or possibly in place of my Katadyn.
This is a basic filtration system that is modeled after modeled after the average municipal water system. Passing through the most course media first. Of course the municipal water system is a bit more complex with more layers and even a chlorination step added. This is a more simple design that simply helps make water safer to drink. The only problem with this system is finding the components to make it. Limestone gravel, sand (the easiest to acquire), and activated charcoal. This system does last for a long while, so if you want to prepare for using this method, I suggest you purchase all items ahead of time. This of course is not something you would carry with you, this is more for the homestead preparation.
This is to set up a water distillation system. The copper tubing is 5/16 to 3/8 ID (inside diameter). You will want type K coiled copper, as it is the most malleable and easiest to work without creasing. If you can not find type K, the you may consider type L. Be ready fro some expense since copper is expensive and type K is currently around $3 per foot and type L is over $2 per foot. Meaning this is not the cheapest option but if you have firewood available this is the best long term option.
A lot of people like to do strictly air coil for the condensing process, but by using the water cooled bucket you can conserve more water losing less to steam. This means you can process a lot more water daily.
Note the diagram shows nylon heat resistant grommets int the holes drilled in both the drinking bucket lid and in the cook pot lid… you may consider using brass NPT through-fittings. They make for a more heat resistant connection.