41

How much sea water can I safely drink? = None If you drink sea water, how much fresh water do you need to drink to off set the sea water you drank? = 2.8 units of distilled water per 1 unit of sea water (to neutralize without adding hydration) The "scientific" answer to this question involves a lot of complex math, human physiology and significant ...


37

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 water evaporates, reforms on the plastic bag (without any salt in it) and then drips into the cup. Slow but far better than drinking sea water.


35

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/gram °C (reference). To raise the temperature of 1 L of water (1000 g) by 80 degrees C (to boiling from room temperature), would be 4.186 * 1000 * 80 = 334,...


35

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 apparatus, whether solar or fire-heated) is the only easily improvised way to desalinate water, but the article I read said he caught and ate fish - that will provide ...


34

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. Clearly there are potential dangers associated with drinking contaminated water but these need to be weighed against the dangers of dehydration. As with most survival ...


27

The question doesn't state what geographical area it's about, and it really isn't possible to give an answer that covers everything. In this answer, I'm only going to deal with pristine backcountry areas in North America, such as the Sierra. In order to interpret the scientific evidence properly, it's necessary to understand some scientific background about ...


24

There is typically no need to purify water collected from natural sources in the wilderness. For example, in a survey of 69 sites in the U.S Sierra Nevada, every site had concentrations of Giardia cysts much too low to make anyone sick.[Rockwell 2002] The perception that backcountry water is unsafe to drink without treatment is folk wisdom that is ...


24

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 needs. The life straw will allow you to purify water sources you find up to a certain degree, but some concerns remain: You first need to actually find water ...


19

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 Hydroperiodide. So there are things besides simple iodine getting into your water. More importantly however, is that many of these things, including the iodine ...


17

I think your assumptions are correct. To my knowledge in a mountain environment you are quite safe as long as you follow some simple rules, which you mostly already named: The water was not standing, i.e. it comes from a stream that is rather fast and the stream is big enough that it is not just a connection of puddles or ponds where the water rinses from ...


15

The key is to always have a trash bag. Your most reliable backwoods method for clean water is condensation, either through natural action, or via a still of some kind. The primary component of this is having large enough suitable material to make said still. If you are depending on natural action, then surface area is still key. Assuming you left your ...


15

If safety is your primary concern, then the only two methods can guarantee safety from major contaminants (microbial or otherwise) these are Distillation and Reverse Osmosis Distillation Boiling alone will leave most contaminants in the water, such as heavy metals, hydrocarbons, etc... multi-stage distillation will both kill pathogens and leave most ...


15

Filter the water right away, when filling the bottle. This way I'm sure the water inside the bottle is safe for drinking. This. Why? The main point for me is accessibility of that water. If you come to a situation where you need fresh water, then it may not just be because you've set up camp, you've got a while to spare and you feel like a drink. It may be ...


14

THE official information can be found on the CDC webpage. The CDC defines the problem in terms of what you're trying to kill: Protozoa, Bacteria, or Viruses. They address each of those in terms of water treatment methods: Boiling, Filtering, Chemical Disinfection, (or now-a-days UV Treatment). Please read what they have to say before you head into the ...


14

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 now, when no one seemed to care before?" Or in other words, we're not talking about how dangerous Giardia is, but rather why people are worried; specifically ...


14

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* bamboo* broad leaves shaped using twigs* birch bark* dig up some clay, create a bowl and throw it in the fire carve a wooden bowl use strips of wood, bound ...


12

If I am using a water-pump filter. Is it necessary to combine this with a water purification tablet? As discussed in this answer and at greater length here, the need to treat backcountry water before drinking it is largely a myth. Neither the filter nor the tablets are needed. You're better off focusing your efforts on avoiding the real reason that ...


12

Once you open it up to toxins, the answer is clearly no, boiling is not enough. There are many examples: Alkali Salt Heavy Metals Blue-green algal toxins, which appear to be present in your photo If you are trying to clear up truly noxious water, try this method: https://outdoors.stackexchange.com/a/351/127


12

The bottom line is there is always SOME risk. Whether to take that risk or not is your choice. Fast running + isolated + high elevation = prettttty low risk. With that said the biggest concern is, unless you are drinking right from the source, you have no idea what has happened upstream from you. There could be a dead animal snagged in the stream, animal ...


12

The terms to google on seem to be "turbidity," "total suspended solids," and "total dissolved solids." TSS refers to solids that can be eliminated by a filter, and TDS to solids that are in particles so small that they get through a filter. High TSS seems to be harmful to fish because it indirectly reduces the amount of oxygen: https://www.ndhealth.gov/WQ/SW/...


12

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 reusable, and not require you to bring specialized gear. You might even be able to wrap the bandana around your pump intake (maybe using a rubber band) and be able ...


11

Boiling eliminates only a certain class of contaminants that can make you ill. Specifically living bacteria and other microorganisms (protozoa, amoeba). It does not purify, or decontaminate the water completely. Certain bacterial and algal toxins can survive boiling and make you sick, and as Russell pointed out, there are also inorganic contaminants that ...


11

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 be testier) alternative to eat/drink. If I am in a desert-like situation, and I've found this water after a long long time, and I am sure its not potable, I'd ...


11

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 quite obvious, isn't it? An article on Backpacker Magazine sums it up: A tricky question. Is water still flowing through? Then it’s working, at least on ...


10

As I understand the technology, your microfilters will not expire on the shelf if maintained and stored properly. Their lifetime is determined by the number of gallons pumped. What can happen is if you don't properly dry out your filter before storing then it will develop mold. In that situation you can decide if it is best to clean the filter or replace it....


10

nope yep (actually, yellow, not purple, thanks Clare) Not in my experience, but I use clarifiers which remove the flavor in the water. Also to clarify from comments, we did this for years before we started carrying a filter and it never damaged our containers. The plastic probably gets more damage from the sunlight caught during hiking than from the ...


10

I'm going to assume that you are employing the SODIS method of water sterilization. To sum up the details of the process, this method is where you fill plastic pop bottles, (PET), up with rather clear water 3/4 full, shake them up, and let them sit in the bright sun for 5+ hours. The mechanism this works by is by utilizing the UV radiation in sunlight. ...


10

According to wildwoodsurvival, the sand helps remove suspended particles. Charcoal helps to remove chemical impurities. The charcoal plays the role of active carbon. The water filtration process use multiple materials, from coarse to fine, to prevent clogging. As a last stage, the charcoal can also help remove some bacterias. Note that the author of the ...


10

Yes. There's nothing wrong with melting snow and then purifying it with a standard water filter. Most of the water in mountain streams was snow at some point anyways. That being said, this is generally going to be a very inefficient way to make water, and if the temperature is below (or really anywhere near) freezing, you're going to be thirsty. I would ...


10

Is this rust by chance? If so, let it dry and it'll be powdery at the bottom. Run your finger on the surface and some will come off on your finger. If it's rust, you may be able to get it clean with some steel wool. Just make sure to keep it dry after use from then on. SmemSeger could be correct and that it's mineral deposits. I usually find those to be ...


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