Hiking : Water sources & water purification

I was having an off-line discussion with a SOTA member about this topic and I thought it is a very interesting topic.

When I go hiking, I always check topo maps very carefully regarding the profile of the mountain what is the best approach, etc. I always try to estimate how long it takes to get there and how difficult it is. Based on this information, I try to gauge how much water I should be carrying with me.

The problem we have in the French Alps (and I am sure in other places) is that in the summer, a lot of the streams that are indicated on a map are actually dry. Another problem is that even if you find a running stream, there are very often very large herds of sheep or similar animals that risk contaminating the water. There are no resources that indicate safe water sources anywhere. It is therefore not easy to find a source of clean water that you can rely on. Due to this I tend to carry large amounts of water on long hikes. I would rather have too much than not enough but it obviously weighs heavily in your pack and the heavier the pack the more you drink :slight_smile:

Sometimes I purify water but found out that the product I was using is now considered as not good enough. I am therefore curious what other fellow hikers out there use to purify and drink water or whether you do it at all?

    1. Boil
    1. Bleach or Drinkwell Chlorine (Sodium Hypohypochlorite)
    1. Hydroclonazone (Tosylchloramide, aka chloramine)
    1. Aquatabs (Sodium dichloro-isocyanurate, aka DCCNa)
    1. Iodine solution 2%
    1. Micropur or Drinkwell (Silver)
    1. Katadyn Mini Carbon or similar (Carbon but no microfilter)
    1. First Need, Miniworks, or similar (Microfilters 0.2µ -> 0.4µ)
    1. Pure it carafe, Voyageur Pentapure (Microfilter w/ iodine)
    1. Combi Katadyn (Microfilter w/ carbon)
    1. Guardian Plus, Pentasport Flask (Microfilter w/ Iodine & carbon)
    1. Katadyn Mini Ceramic or Pocket filter (Microfilter w/ silver)
    1. I mostly carry all my water needs
    1. I only drink pastis

0 voters

In the past I used hydroclonazone but it is considered not good enough nowadays. It also takes 1 hour to purify the water. The advantage was that the water did not taste like hell.

Typically whether mechanical or chemical processes or a combination thereof, some are better than others for certain tasks. Usually people look at the ability to remove: particulate matter, bacteria, viruses, parasites.

A good map tool pointing clean reliable water sources and an efficient lightweight system would be awesome to have. Imagine having to carry less water on a long hike and re-filling at clean locations or with a tool to purify the water! A nice dream to have!

Since I drink like a camel I am looking into various solutions. Looking forward to hear about what you guys use.

Where water is certain, e.g. a lake or known large stream, I’ll take a UV purifier, such as Steripen. Otherwise, which is almost always in Southern Arizona, I’ll carry all the water. 7 Liters is the most so far. I also drink like a camel.
You may want to add UV purifiers to your voting list.



Thanks Ken,

I have heard about the UV pens. I guess you need batteries. I’ll have to read-up on the efficiency of these.
Most water for me is probably 5L. My friends would mostly carry 1/2 of what I carry as they are much fitter than I am.

I cannot modify the poll after 5 minutes. A moderator has to do it.
If one of the mods could add UV filters to the poll it would be much appreciated.


Apart from carrying typically 3 litres in the back pack bladder, also have a Lifestraw Go water bottle & Steripen which has an internal Lion battery & usb charge input…
Really depends on the quality of available water as to what / if anything is done with it. The Lifestraw & Steripen only taken on multi day activities.


Hello from Slovenia,

come to our mountains and drink water from nature without filter.
Clean water is everywhere and you need just a 1 liter bottle in rucksack.

Best regards


Thanks, straws look pretty light.
Guessing water sources can be a big deal in some areas of Australia.

Sounds like paradise.

We have very clean streams in the French Alps too but you never know whether local animals have contaminated it.
I remember fishing in this very pristine stream in some remote valley. It looked really crystal clear.
After a few hundred meters up the stream I found the carcass of a chamois rotting in the water.
It looks like an avalanche had killed it and swept it there.
I can only imagine the type of bacteria that was in that water.
So, even in clear water streams you never know what’s in the water above you and you have to be careful.
You’re always taking a chance by drinking straight out of stream.

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This can be a big problem especially in the early spring when mountain animals are at their most vulnerable. When they get sick, they often head to a water source to drink, which they don’t normally do, since they get most of their water from vegetation. The sick animal will then sometimes die close to the water course and the water can become contaminated. So, just because a stream appears to be clean and fresh, doesn’t mean it’s safe to drink. Better to boil it, filter it, or treat it with something.

The average filtration systems available to hikers can’t filter viruses - the pores in the filters are much larger than the viruses, which pass straight through. There are filtration systems available which can filter viruses, but they’re expensive and heavy; chemical or UV treatment to eliminate viruses is a cheaper and lighter alternative.

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Filtration systems usually do not have filters with pores <0.1µm while viruses are around 0.01µm.
Viruses tend to attach themselves to particulate matters that can be filtered out but if some are free-floating it will not work.
Chemical treatments are pretty good but do not guarantee full elimination. Still probably best after boiling.
Boiling is the best way to get rid of viruses. Some are tougher than others though, Hepatitis A requires 5 minutes of boiling to be de-activated.

For UV pens it looks like the jury is still out on this one. The EPA for example does not approve UV devices carried by hikers it seems. UV treatment works in clear water only as well so you need to filter turbid water first.

All a bit complicated…

Hello again,
See the following for an in-depth and up to date discussion of virtually everything that is available:

Keep on hiking!

Ken, K6HPX

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Interesting review.

It looks like the Steripen is working on addressing the duration issue.

There was a survey recently of multi-day hikers on the Appalachian trail. They were asked what they were using to take care of their water. The #1 answer: Aquatabs (ranked 13 on the OutdoorGearLab review).

I have read somewhere that there can be large discrepancies between what manufacturers claim and actual efficacy of some of the products. Most online reviews take manufacturers’ claims at face value without any lab tests.

One review I saw with actual lab tests ended-up placing the Combi Katadyn, Guardian Plus and the Pentasport flask among the top spots.

Roger that; when looking at big elevation gains and long distances with water present, I’ll be using that as well.
Used Iodine in the late sixties in SE Asia rain forests, but was going through sooo much water, that toxicity from the Iodine tabs was a genuine concern.

Steripen has a military model that is more robust, and it has an end that will stick down into a US G.I. canteen neck.


Yes Iodine can be toxic and batter your thyroid if you use it too much. I can imagine how much water is needed when hiking in the rainforest… Steripen sounds like an attractive solution in combination with a lightweight microfilter, maybe like a sawyer mini to remove particulate matter first.


I have yet to attempt the sort of extended hike that would make these things necessary, but the subject is interesting all the same.

I’m curious about the references to virus, and how many of the products seem to give no protection - in what circumstance (apart from imminent death from dehydration) would you not be concerned about virus contamination…?


Hi Brian,

I think everybody would be concerned about virus infections. It seems boiling it the only way to have some peace of mind on this subject (up to 5 minutes for hepatitis A).

In the end it probably comes down to personal choices and the type of environment you are hiking in. It is kind of like when you buy a car. How many advanced safety features can you afford. In the old days airbags and ABS breaks were not standard on all cars and buyers had to decide how many features they could afford and whether it was money well spent.

When it comes to hiking and water filtration systems with regards to viruses, it is probably a similar choice. It has less to do with cost but more to do with weight and expected efficiency and the likelihood of getting infected based on the type of terrain you are hiking in (Amazonian jungle vs dry grassland for example).

Personally, given the environment I am typically hiking in, I am more worried about contracting Brucellosis (bacteria) than contracting a virus. It does not mean I am not worried about contracting a virus but I think that where I typically hike, the odds of getting infected by a bacteria are higher than that of getting infected by a virus (I may be wrong).

It is a personal choice and everybody’s risk assessment will vary. If you want to be safe you can carry a stove and thoroughly boil all the water you intend on drinking. Are you willing to put-up with the extra weight and the time it will take to set-up and boil it every time? Everybody’s answer will depend.

I also do mostly day hikes but considering longer hikes this season away from huts which is why I have been thinking about this topic. I have also ran out of water in the past and met people who had ran out of water as well. I am thinking that having that extra bit of gear that may allow you to consume water that would otherwise get you sick is not such a bad idea. Hearing about people’s experiences on that front is always helpful and interesting.


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Interesting topic, on most hikes I do, which are rarely extensive affairs, I usually carry the water I expect to need, but always have a sawyer mini in my bag along with some puritabs, on most trips I also take along the jetboil & that covers all bases for me, the filter & tabs can sit inside the jetboil easily so takes up no more space than the jetfoil alone, I carry the gas & burner in a separate pouch along with my spork & wipes, the extra weight is minimal, I also carry a couple of other ways to make fire with me just in case the jetboil fails which up to now it hasn’t.


Thanks Arnaud and Neil,

Only once have I run low on water. I was carrying 2.5 litres, on a hot all day hike. I decided to cut the walk short, and drank the last of my water when in site of the car, where I had plenty more.

I did pass a stream, which could have been useful if I had some purification kit. On the other hand, for occasional use like that, I’m not qualified to assess the risk - to follow your analogy Arnaud, I can see brake shoes and airbags, but I can’t see or assess a virus presence! Maybe I should do a little more research.

Boiling is perhaps the safest, and I do have a tiny stove, but boiling and cooling a quantity of water is not a quick process in the context of a day’s hike…

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I have reached similar conclusions to you.

I use a Jetboil Minimo to melt snow in Japan in the winter. I am probably thinking to get another one for France and leave it there. The piezoelectric starter on the Jet boil has not failed me either so far. I am also thinking to get the Sawyer mini, not for regular usage but more for a “just in case” type of situation. With the 100g gas canister I cannot put anything else in the Jetboil but not a big issue, I usually carry large packs with extra space.


I remember running out of water when activating F/AM-035 with my friend Thierry, F4EGG in 2014.

There is a super-long approach to the col before tackling the summit. That approach is in a bowl that somehow seems to intensify the sun’s rays. I had taken 5L of water. It still was not enough. I ran out of water on the way back half-way through that scorching bowl. There was no water source, it was like a desert. The summit had some snow though, so if I had had a stove I could have replenished my supply earlier on. By the time I reached the car I had no more saliva in my mouth. My entire mouth, throat, lips all felt as if I had sucked on some super hot sand. I arrived at the car feeling completely drained. Thankfully there was a hut selling cold water at the parking lot. I went to buy some. When it was time to pay, the guy in front of me decided he would try to get a date with the gal running the cashier… By that time I could not take it anymore, I opened the water in the shop and drank it on the spot before paying for it.

So running out of water sucks. Every hike is different. In that case, a Sawyer Mini or similar wouldn’t have helped but a stove at the summit would have done the trick.

Lesson learnt!

I like #14!

But when I need to I carry a Sawyer gravity filter set-up.

Richard // N2GBR

p.s. On the AT it seems common to use Aqua-mira (SP) which is a two-part product and takes ~15mins

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