Grayl Water Purifier
It’s likely you already know how to use the Grayl Water Purifier without outright knowing it. Built like a french press, just fill the outer cup with suspect water, press the inner cup into it with a steady downwards pressure — like you’re sequestering coffee grinds — then drink the clean resulting water. Each Grayl comes with one of three filters: a tap filter, which removes chemicals and heavy metals; a trail filter which does the above as well as filtering out bacteria, protozoan cysts; and a Travel purifier, which also traps viruses. Each is good for filtering a total of 40 gallons, or about 300 uses.
Grab one at Amazon – $60 to $90