Non-industrial water filtration
In polluted or even unfiltered mountain water there are lots of parasitic organisms and inorganic chemicals that are dangerous to humans.
Common organisms:
- giardia causes gastroenteritis
- cryptosporidium causes gastroenteritis
Common Chemicals:
A reverse osmosis filter is larger and requires more energy than pressure-gradient model that fits on a water faucet.
In the handheld sizes, there are gravity based filters like brita and handheld pumps: these are usually based on active carbon filtration plus some other technologies.
For minimal energy, "chlorine" tablets can be used to kill off organisms. However, these chlorine tablets should be used within 6 months, or they lose their effectiveness. Keep the container sealed, because air quikens its detoriation.