So somehow I ended up in a legit third world country, and suddenly all those things I read about survival could actually be of use to people

often people have water tanks, but no filtration or purification systems
what would the best way of rigging a cheap but long term gravity water filter?
I was thinking charcoal, but not sure if it would make more sense mounting it above or below the water tank
people here just can't afford bottled water

also cold storage without electricity, people here just air their foodstuffs and so much is wasted
pickling is still a crude practice here, with open air fermentation instead of sterilizing containers

how do you get rid of intestinal parasites without proper medicine?
does garlic really work?

in some places they just need money, but over here locals just don't have the education and skills to get things done
what about venereal disease?