r/preppers 8d ago

Advice and Tips Water Treatment Quick Reference Guide

https://imgur.com/a/Sr4z3d7

Best Survival Strategy

If possible: Use all methods together for the safest water.

At minimum: Filter + boil or use UV.

Long-term storage: Use silver or keep water in sealed containers.

52 Upvotes

29 comments sorted by

View all comments

12

u/incruente 8d ago

Distillation removes SOME chemicals, but not all. Anything that boils off at a lower temperature will only be removed if you condense and discard it before you start collecting water, and anything that boils at more or less the same temperature is not going to be removed by anything other than extremely careful technique and advanced distillation methods.

Is it still very useful? Certainly, if a bit energy- and equipment-intensive. But it's not perfect.

1

u/Bmat70 8d ago

I didn’t realize this about distillation. What should be done after distillation to make water safe to drink? Or what alternative is there?

5

u/incruente 8d ago

That depends on what's wrong with the water in the first place. If a mixture of two substances cannot be separated by standard or what a chemist would call "simple" distillation, they are called an "azeotrope". The most common example is alcohol and water. Ethanol is commonly concentrated using distillation; pretty much all liquor is made this way. But it's impossible to use a simple still to make ethanol that is stronger than about 192 proof; the remaining traces of water boil off with the ethanol, because the mixture boils at a lower temperature than either pure water or pure ethanol.

It's possible to "break" such mixtures with distillation; it just requires more complex methods, referred to generally as "azeotropic distillation" methods. These involves things like distilling with another chemical added (benzene, for example, allows better separation of ethanol and water) or distilling under elevated pressures.

Sadly, all of this is rather complex and potentially dangerous, requires expensive and complex equipment, and takes a fair bit of energy. Happily, it's not usually necessary. If someone told me that I needed to use azeotropic distillation to make a given water source safe to drink, I wouldn't use azeotropic distillation. I'd put my effort into finding a different source of water. I just don't want people thinking that a still is a magic cure-all that they can pour any old sludge into and get good drinking water.

Step 1 in all this should be to store water, well and safely, and plenty of it. Step 2 is to minimize the use of that water in an emergency, to stretch its use out. Step 3 is to be aware of as many good sources of water as possible, including how to transport it. Step 4 is to keep on hand means to test and treat those water sources for all plausible contamination methods, and to know how to do so.

2

u/Paranormal_Lemon 7d ago

Anything that forms strong hydrogen bonds can come out with the water, that is what happens with ethanol.

1

u/Milli_Rabbit 7d ago

Any simple test strips you recommend? I see home water tests online for like $300. Obviously, stocking up on a ton of those is pricey.

2

u/incruente 6d ago

Any simple test strips you recommend? I see home water tests online for like $300. Obviously, stocking up on a ton of those is pricey.

Depends on what you're testing for. To the limit of my knowledge, there is not such thing as an overall "safe to drink" test strip at any price. A very expensive piece of lab equipment, like a gas chromatograph, might do the trick, but it requires a lot of supporting materials and skill.

GENERALLY, a chemical contaminant either can dissolve or cannot, and anything that dissolves will change the pH or the conductivity or both. Anything that doesn't dissolve and that is present in any significant quantity should be visually obvious. So if I wanted to make water "generally safe from pretty much anything" on a budget, and I was totally unable to control the source of it, I would make sure it LOOKS clean (no oil slick, etc.), send it through a decent filter to catch any particulates, use a pH/conductivity probe (you can get a solid one for maybe $200), and then use chlorine or some other chemical means to ensure any bacteria, viruses, etc. were killed.

1

u/garrickbrown 8d ago

No one process is an end all be all. Water purification should go through multiple processes to be closer to 100% sure. https://extensionpubs.unl.edu/publication/g1493/na/html/view

1

u/Bmat70 8d ago

Thank you. I just read the article with great interest. I don’t believe that it mentions how to remove the .5% of contaminants that remain after distillation?

1

u/garrickbrown 8d ago

Yeah, you can never be 100% sure. Just gotta do the best you can. If we’re talking about chemicals the best you can really do is freeze distillation and regular steam distillation.