37 votes
Accepted

Ways to desalinate water when "lost at sea"?

Salt dissolves in water so will pass though a normal filter or cloth. You can try that with a coffee filter at home. So there's definitely an error in the article. A still (i.e. distillation ...
Chris H's user avatar
  • 26.3k
37 votes

Ways to desalinate water when "lost at sea"?

You can place an empty cup in the middle of a lightly filled bucket of sea water. You then place a plastic bag over the bucket, with a stone in the middle so it has a dip in it over the cup. The sea ...
Robin's user avatar
  • 471
35 votes
Accepted

Can you boil/decontaminate water with heat from a magnifying glass?

Let's do some back-of-the-envelope calculations. The specific heat of water is the amount of energy needed to raise the temperature of a particular amount of water by 1 degree C. This is 4.186 joules/...
Greg Hewgill's user avatar
  • 1,543
34 votes
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In a survival situation, should I drink unpurified water?

Dehydration will very quickly reduce your ability to undertake the activities required to survive and so finding and conserving water should be a very high priority in any survival situation. ...
Chris Johns's user avatar
  • 6,202
24 votes
Accepted

Does a life-straw replace my water while hiking?

Generally speaking, no. Arguably you should never go for out for any kind of extended exhausting activity without ensuring proper hydration, i.e. packing enough fluids at least for your immediate ...
fgysin's user avatar
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19 votes
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Iodine tablet correct use and efficiency

Welcome back to good old chemistry class! Apologies if this gives you nightmares. First, the tablets used for water purification are not elemental iodine, but a crystal form called Tetraglycine ...
cobaltduck's user avatar
  • 5,168
16 votes

is water filter log reduction multiplicative?

No. Filters don't work like that, though there can be some benefit to double filtration as I'll explain below. I don't know the mathematics of it though. Basically what happens inside a filter is that ...
bob1's user avatar
  • 10.2k
14 votes

Why are people so worried about Giardia?

I'm going to chime in on a more practical answer. The question is not "What is the scientific case for Giardia". The question is "Why are people so scared of it?" "Or why is everyone so scared of it ...
Russell Steen's user avatar
14 votes
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How do you boil water without a proper container?

A watertight container is what is required here. The best thing is metal but if we're without this you can use plastic bottles on the shoreline folded paper a hollowed out and charred piece of wood* ...
Chris J's user avatar
  • 1,778
13 votes
Accepted

How do I test my water filter?

General information Unfortunately the only real way to get your water filter checked is to send a water sample to a lab. You may only want to check whether water is still flowing through, but that's ...
OddDeer's user avatar
  • 23.5k
13 votes
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Is pouring boiling water into a plastic Nalgene bad for you?

Most Nalgene bottles are designed to be able to stand up to boiling water. Today, many hikers and others recognize the distinctive appearance of Nalgene-branded bottles. Its laboratory pedigree is ...
Charlie Brumbaugh's user avatar
13 votes

Filtering fine silt/mud from water (not necessarily bacteria etc.)

While coffee filters would work great as suggested in a different answer I would probably just use something I was going to bring anyway like a handkerchief. That should work reasonably well, be ...
Erik's user avatar
  • 9,668
12 votes
Accepted

UK blanket bog peatland water - safe to drink?

EDITED TO ADD: Please also read the other answer by cbeleites unhappy with SX about the risk of heavy metal contamination. The information in my original answer (below) is still accurate regarding ...
csk's user avatar
  • 4,374
11 votes

In a survival situation, should I drink unpurified water?

Dehydration will kill you before Giardia or cholera does. So, I'd first take a measure of where I am, do I absolutely need to drink the water is question, or is there any other better (safer, need not ...
WedaPashi's user avatar
  • 31.7k
10 votes

Is pouring boiling water into a plastic Nalgene bad for you?

Nalgene is owned by Fisher Scientific. They do lab bottles, recreational bottles, and lab equipment. Boiling water is a probable exposure. If bad thing happen the lawyers would be putting out ...
paparazzo's user avatar
  • 7,166
10 votes

Ways to desalinate water when "lost at sea"?

Disclaimer: This is not safe. This is not well tested. This belongs here, not on the other question. This is weak evidence in collaboration for the drinking seawater claim. On request by Seth ...
Joshua's user avatar
  • 613
10 votes
Accepted

Filtering fine silt/mud from water (not necessarily bacteria etc.)

Leaving aside your assertion that water in the high mountains is likely to be biologically safe. The answer depends on how big the particulates are. The smaller they are, the harder it is to find an ...
bob1's user avatar
  • 10.2k
9 votes
Accepted

How do you make an emergency water filter and purifier?

Gravity Filters Cone Filter Much like Charlie's gravity filter in a bottle, this filter is essentially the same, only using a cone of tree bark in place of the bottle, and using extra filtration ...
9 votes

How do you make an emergency water filter and purifier?

Here is what I have found for a very basic set up with a cheap water bottle. The water will be pored through the top through gravel, sand, charcoal and finally either a screen or another mechanism ...
Charlie Brumbaugh's user avatar
9 votes

Why are people so worried about Giardia?

Why are People so Worried About Giardia? Because giardia is commonly found in backcountry water and it is known to make some people very sick. The EPA says [giardia] "Cysts have been found all months ...
Buck Nelson's user avatar
9 votes
Accepted

How can I desalinate ocean water enough for cleaning or showering?

The problem is that desalinating water is hard; nearly desalinating it isn't much easier (it would be possible to design a bad reverse osmosis system but there isn't much market for that). Instead if ...
Chris H's user avatar
  • 26.3k
8 votes

Why are people so worried about Giardia?

Some excellent research-based answers here, so I'll focus on the practical implications. First, and most importantly: Most intestinal infections in the backcountry aren't caused by bad water - ...
Tullochgorum's user avatar
  • 11.7k
8 votes

When should I boil water before distilling it?

I still think this is off topic but I don't agree with a posted answer. If you are talking hydrocarbons they are pretty toxic to humans even in small concentrations. A spill minor compared to the ...
paparazzo's user avatar
  • 7,166
8 votes
Accepted

What are the most likely causes of unfilterable water contamination in upland UK areas?

Viral infection Assuming you have a quality filter which genuinely removes bacteria and protozoa, you are probably safer from viral infection than you think. Viruses are quite likely to be present ...
Tullochgorum's user avatar
  • 11.7k
8 votes

Can any automotive fluids be made safe to drink?

None of these fluids can be made "safe" for consumption. Most of these liquids are oil based with these exceptionn: battery fluid: is a strong acid, which is diluted with water washer fluid: water ...
knitti's user avatar
  • 1,461
8 votes
Accepted

Can any automotive fluids be made safe to drink?

There are three fluids in your car that contain water: the battery electrolyte, the washer fluid, and the coolant. Everything else is hydrocarbon-based, and in a properly-functioning car, contains no ...
Mark's user avatar
  • 2,980
8 votes
Accepted

What is the minimum amount of water per day to survive?

According to NAP.edu, the minimal (obligatory) daily water loss for an adult is at least 1 liter (~1 quart), which includes losses by the urine, feces, insensible perspiration and breathing (but not ...
Jan's user avatar
  • 1,329
7 votes
Accepted

Can sunlight be used to purify water?

It is possible, here is the Wikipedia article on it. You do have to check that the plastic in the waterbottle doesn't prevent the UV light peneatrating the bottle. Some glass or PVC materials may ...
Charlie Brumbaugh's user avatar
7 votes
Accepted

Drinking water in Dartmoor

I live by Dartmoor and walk there regularly (in fact I was up there earlier today). The moor carries a significant stock of sheep, cattle and ponies. I've heard of tests that found much of the water ...
Tullochgorum's user avatar
  • 11.7k

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