Purifying water in the field

Factual Questions
1

I am familiar with using a solar still to purify and/or capture water from urine, vegetation, sea water, etc. Is there a field expedient method for purifying water that has been contaminated by, for example, gasoline? I realize that you are unlikely to encounter that in a survival situation, but it is possible.

Rob

2

Petrol products will not mix with water so it is a matter of separation. It would seem to be one of the easiest ways to get water, if needed just stick your head below the gas level and drink.

3

Maybe not. Gasoline in the US and in Europe has around 1% benzene added as an octane booster. Benzene is soluble in water, to the tune of around 0.8 g/L. There are probably other water soluble toxins in gasoline as well, but the benzene alone will render it undrinkable.

4

Chemical contamination is probably not solvable by the unequipped person.

Biological contamination is fairly straight forward. Either boil, treat with iodine (drops/tablets), or chlorine (bleach). Time, quantities, and dilutions will be left to the reader as an exercise.

5

Are filters suitable for removing chemical contamination? I would think a reverse-osmosis filter would do the trick, but I am not sure if things like Katadyn filters do that. Is there a field expedient means of fractional distillation? If a substance like benzene is dissolved in the water, can it be separated through distillation through a solar still? Is there a way to deal with suspended solids or heavy metals?

Thanks,
Rob

6

Activated charcoal will adsorb most organic compounds. It’s quite good at grabbing benzene, for instance. Suspended solids (or turbidity) are usually handled by sand filtration.

7

I’d go with several levels of activated charcoal. Reverse Osmosis can get rid of a lot as well.

I would go: coarse filter -> fine filter -> ion exchange resin -> charcoal 1 -> charcoal 2 -> RO

At the bottom of the Grand Canyon, we simply had a little pump filter. It may even have been a hand pumped RO unit. Supposedly, it took anything nasty out. I have no idea how well it would work with urine. I think it would be sanitary, but not tasty.

8

So, if I’m reading this right…

Filter through a bed of activated charcoal, and sand. Probably best in layers? This removes solids, and organic compounds.

Filter and/or treat to remove bacterial/fungal/parasitic nasties?

Pray?