The Science of Water

[malcolmc]

Thanks for that BR. I appreciate the time you’ve put in.

[Staghound]

I have just read the original article in this thread with interest. For quite a few years now we have lived in isolated houses with private water supplies, in the first case from a spring and currently from a well occasionally topped up by a nearby stream (used by farm stock) In neither case has the water been either filtered or chemically treated. With this in mind I always recommend that visitors boil water before drinking just in case, however in general we seem to be healthy and less prone to stomach bugs than many of our friends who depend on mains tap water. I also tend to be fairly blase about drinking directly from the local watercourses. Admittedly this is quite an isolated area so there is not much chemical contamination to worry about. However I wonder if there is any evidence that routine exposure to the common waterborne bugs, ie. e. coli, cryptospyridium etc. can lead to increased resistance, after all our dogs, stock and the local wildlife seem to stay healthy on the stuff?

I think in other areas I would be less casual about the water I drank.

Yours probably about to croak from cholera, liver fluke, typhus, e.coli and tapeworm:

Steve

[Nelis]

HI Red,

Great article, nice info. A while back when I was searching for a waterfilter I indeed became very confused about all the ins and outs of the modern filters.

Now I don't want to be a knowitall, but just one little comment, as a whisky and whiskey fan I know somewhat about distillling, and I believe it are the chemicals with a higher boiling point then water that you can remove using a still. If you want to remove the chemicals with a lower boiling point, you would need a thermometer and only collect the distilled fluids as long as the water in the still is at 100 degree's (at 1 atmospheric pressure). Not before it gets to 100 degrees, and not when the water gets hotter. Even then there will be a risk of contaminating your water with chemical residu left in the condensor.

Also when I bought my filter, the people who sold it to me claimed that there are no filter devices that can remove all virusses from water, but not to worry to much about this because waterborne virusses are very rare in western europe, what are your thoughts on this ?

[British Red]

Niels,

Distilling is odd. Clearly it depends if you are condensing vapour or keeping the donor liquid as to what does what.

The way I see distillation in the UK at least is its one of the only ways to reliably remove heavy metals etc. (all of them). So condensed steam will have all living contaminents killed by heat, particulates left behind and most metals etc. left behind. However the distillate could still containe alcohols and other VOCs (volatile organic chemicals)

The people who sold you your filter were plain wrong I'm afraid - Lifesaver systems are one type of portable filter for viruses and I believe there are others. I haven't used one myself (they are over £100) but I hear good things



Red

[AJB]

Hi Red,

That was a really good read, many thanks for the effort it must have taken to produce. Would it be possible to make your piece on fire available again, I’d like to read that.

I own a PreMac Model PWP which I have to admit I’ve never used in anger. I saw them first launched at COPEX many years ago, and when I saw it cheep I had to buy it - I’m a kit junky! Would anyone have an opinion on them? Red if you had to recommend one “perfect” (if there is such a thing) filter for back packing what would it be? There seem to be so many on the market but so few seem to cover all the bases, is this because the risks they ignore are statistically irrelevant or do they hope their users get lucky – it’s such a confusing choice (or it would be if I needed one – I just love kit)

Thanks again.

[gregorach]

The PWP is perfectly adequate for almost any conceivable use, except where you need to remove chemical contaminants. Biologically, it's excellent.

There is no "perfect" filter - all have their limitations and drawbacks, whether it be inability to deal with chemical contamination, limited lifetime, weight, price, etc, etc... The question is what do you want from a filter? Me, I'm quite happy with my Pre-Mac SWP - because although it has limited capacity, and thus works out quite expensive on a per-Litre basis, it's very small and light. Other people much prefer larger / heavier / more expensive filters which have replaceable cartridges, or ceramic plate filters which don't involve replacement.

As always, it's a question of trade-offs.

[AJB]

This seems pretty good...

http://www.msrgear.com/watertreatment/sweetpure.asp

...coments?

Don't you just love this stuff (or is it just me - gulp!)

Andy

[British Red]

Hi Red,

That was a really good read, many thanks for the effort it must have taken to produce. Would it be possible to make your piece on fire available again, I’d like to read that.

I own a PreMac Model PWP which I have to admit I’ve never used in anger. I saw them first launched at COPEX many years ago, and when I saw it cheep I had to buy it - I’m a kit junky! Would anyone have an opinion on them? Red if you had to recommend one “perfect” (if there is such a thing) filter for back packing what would it be? There seem to be so many on the market but so few seem to cover all the bases, is this because the risks they ignore are statistically irrelevant or do they hope their users get lucky – it’s such a confusing choice (or it would be if I needed one – I just love kit)

Thanks again.

No worries

Here is the Fire article

http://www.bushcraftuk.com/forum/showthread.php?t=18056

I use a milbank bag and boil most places - failing that I have a pre-mac where size is a huge issue or where I need to suck up water from shallow pools.

Red

[AJB]

Many thanks Red

[AJB]

The fire thread was a cracking read, many thanks Red.

[sirex]

where does aqua-mira fit into all this ? im considering using a milbank bag / aqua mira combo. ill prolly boil too for good measure, but maybe not.

[British Red]

Aqua Mira make both filters and chemical decontaminants. I assume from your question that you mean either the drops or tablets?

If using these they form an alternative to boiling. If you plan to boil, then leave out the drops / tablets as both the tablets and boiling perform the same purpose of killing micro organisms.

Red

[sirex]

ok thats great avoiding boiling would be useful as i dont want to use more gas than i need, and i dont want to start lighting fires.

great thread

[Wallenstein]

This site...

http://www.survivaltopics.com/surviv...to-boil-water/
http://www.survivaltopics.com/surviv...led-revisited/

... suggests that the need to boil water for any extended length of time is unneccesary.

It contains the following quote:

"According to the Wilderness Medical Society, water temperatures above 160° F (70° C) kill all pathogens within 30 minutes and above 185° F (85° C) within a few minutes. So in the time it takes for the water to reach the boiling point (212° F or 100° C) from 160° F (70° C), all pathogens will be killed, even at high altitude."

Just wondered whether this is viewed as dangerous advice or whether fuel savings can be made by limiting purification to boiling-point-and-no-more heating?

[British Red]

Well now - boiling point is a movable feast. In the article I discuss boiling at the summit of Everest (just as the most extreme example you can get). A rolling boil on Everest may not be sufficient unless held for a while.

In the UK achieveing a rolling boil if there are no suspended particulates should be quite sufficient in my book.

Lets face it - common sense implies boiling for a little longer if in any doubt

Red

[Perfects]

Thanks a lot British Red, that really is very useful to me - being a beginner.

[JoyR]

Really good to see a very well researched, accurate and relevant post, particularly on a topic as important as this. I read it with interest, and admit to now knowing far more than I did! Cheers for that

[WhichDoctor]

That really is a fascinating article, really comprehensive.

Theres just one question springs to mind. I have a aquarium and when adding water to it I use a water treatment that removes the clarine, but it says that it also removes heavy metals as well by binding to them somehow. Is there anything like that for drinkingwater, I mean a chemical treatment that could remove heavy metals and the like?

Maybe its just a gimmick on my aquarium stuff and isn't really effective.

[burning]

Thanks for taking the trouble, good read...... pm incoming

[Steve M]

Fantastically informative, thanks. I was considering Survival Straw at one point, now I'm not.

[taws6]

This is a really good thread.
I'm still slightly unsure about river water though.

There is only really 1 big river around here with farmland, industry & sewage plants along it, making me worry that filer and boiling/chemical wouldn't remove the heavy chemicals.
There are some VERY stagnant pools around too, but I don't like the idea of living off of those for a period of time either.
I can't carry all that water, and would prefer to stay away from civilisation for a week / 10 days, and need a system that is portable.
I could use a carbon filter to remove some of the chemicals / heavy metals (after filter & boil / chemical), but am I being a bit paranoid, considering they are extreamly diluted?

Mabey there's another way I haven't considered?

Thanks for the help,
Paul.

[British Red]

To be honest in the UK, a good carbon ceramic filter followed by either a chmical or heat treatment to veal with any virus contaminant is probably all that you need.

We don't have much in the way of very serious heavy metal and chemical pollutants in the rivers. Sewage outflow will be fine treated that way, industry and farmers will be prosecuted for anything that doesn't deal with too.

Never say never but its good enough for me

Red

[taws6]

Great, thanks for that, I'll get myself a carbon ceramic filter.

[thebeatmeister]

A Belting read sir, many thanks for the time and effort you've put into that.
I've been lucky enough to have high mountain streams to fill up from whenever i've found myself running a bit short which are generally quite safe. I am aware of and have practiced several means of water collection and cleaning but have never had to use them in a crunch situation yet. It'd be great to hear anyone's experiences, mishaps, or anecdotes from any experiences they might have had................
It might also be worth mentioning legionella pneumophila which causes legionere's disease - a form of pneumonia - which can be fairly bad in the young, old or those that may have a battered immune system. It causes flu-like symptoms with a cough at it's mildest. It's found everywhere and anywhere where there's water particularly in ponds and still water and loves temperatures between 25-50 degrees C so consider pools/ponds in warm weather to be a risk. A good boil or a chlorine tab will nuke it though.
thanks again

[taws6]

So how about the really stagnant, smelly ponds around here, would a filter and boil produce safe water from these conditions?
(Agreed, not the best source!)

Thanks for the advise.

[Steve M]

We made filters on a coastal course I was helping out on this weekend. The gully water was nearly black. With our sand, charcoal, grass and pebble filters, we could get the water clear. Boil that (within guidelines above) and it's biologically safe. The only thing you have to worry about from that point is chemical impurities, which will need distilling out. Depends where the water has come from.

[taws6]

Thanks for the advise Steve

[Breeze]

Nelis was not told wrongly. For a couple of years the British owner of Lifesaver claimed his filters' pores were 0.02 microns all over his site as the unique selling point then he removed such specifications or at least I can't find it on his site which amounts to petty the same as removing it in practice. Now this is funny as this spec was at the heart of making his products 'unique' as he claimed. This was not true as a previous filter model by Sawyer had the same spec. He also claimed to have invented this after watching the Tsunami disaster and out of humanitarian concerns. Again not true as he is using fine hollow fibre filters used for years in municipal water treatment centres which were invented by others. On his US distributor site recently they claim the pores are 0.015 micron which is funny as they do not make such claims here or if they do it is buried in the small print somewhere which I doubt. I imagine it is still 0.02 microns. This would still allow viruses through which can be as small as 0.01 microns as Red pointed out in the OP. Which brings us to the last false claim by Lifesaver's owner since the start that his products remove all viruses and the resultant water is viral free. Finally the prices he charges to ordinary users and even for disaster areas and humanitarian purposes are outrageously expensive. You might have seen him on Dragon's Den where he got some money on his spray that gets every last drop out based on 'his invented hollow fibre', same thing, which was in fact invented long before by others.

Sawyer which is one of the industry leaders alongside Katadyn and MSR has brought out a new range of 0.02 micron filters based on the same hollow fibre they had before Lifesaver (despite claims) but in a few new configurations (see the first 2 links). They claim that these remove 'most' viruses in a few places but not everywhere on their marketing (damn corporations). They can be cleaned with reverse water flow from a tap and they last virtually for ever, well guaranteed for 1 million gallons. I only found out about their new range last week but alas can not find any distributor for them in the UK so I'll have to wait till I visit the States next time. A friend of mine there had their first 0.02 and was happy, the general feedback has been good on that for the last couple of years too. If someone wants to make a small fortune, they can start importing their viral range, half of their cheaper products go down to 0.1 micron which is still better than the usual 0.2. If anyone does get them or knows where to buy one here, I'll be interested in getting one as I could use them in travels to Europe and Asia and they are much cheaper at around $100 (see last link below) than other 0.02 spec products. Bigger Walmarts carry their filters a little cheaper than camp shops. The most popular general filter types now manufactured by all the big brands, taking over from the old pumps, are the bottles for the usual traveler and the inline filters for backpackers like us for camp use which have good flow rates these days and require no work and pack tiny and light. A cheap carbon filter in serial configuration is advised on inlines to improve taste. I suspect MSR and Katadyn will go down to 0.02 micron within a year or two as well with new products while keeping the cheaper range as with Sawyer who also only had one 0.02 till recently. 0.02 is particularly useful in Asia but increasingly viral infections are on the rise in the USA and Europe too but nowhere near as bad as Asia.

Thanks for the great OP and the Fire article too British Red, made it into a pdf for my future reference.

http://www.sawyerproducts.com/viral.htm
http://www.rei.com/gear/feature/sear...or_link/Sawyer
http://www.rei.com/product/778046
http://www.rei.com/product/781792

[VtBlackdog]

didn't know about the effect of altitude on boiling, thanks for the info!

[Wildpacker]

Always a difficult subject as some people are more sensitive than others to contaminants. I prefer the simple milbank and boil approach and have often just drunk the water from rivers untreated. Cryptospyridium and other cysts normally only give yu a 24 hour bout of 'spanish tummy' and then leave you alone. Some may find it seriously debilitating though. The last time I had it was over thirty years ago when drinking untreated from the Medway in Kent when I had no kit with me. Heavy metals I don't worry about too much. In my youth the water was piped to my house in lead pipes and we weren't so careful with the others as we are now. And I suspect the vegetables you eat may have their fair share in them anyway.
It's really a case of each to their own I'm afraid. But while custom filtration systems are probably good, they are too bulky and heavy to take on a serious walk - and the filters will probably run out just when you need them.