The Science of Water

[HarrogateTobias]

what is the name of the "high tech" 58 water bottle pump? very interested as i might be afghan in the next few years?

[British Red]

Its a PreMac MWP

http://www.pre-mac.com/MIL_P1.HTM

[raspberryjam]

That was very well written, well done

to add to the boiling/temp/alt debate...

"Heating water to a high enough temperature for a long enough time will kill all dangerous organisms. Advice from reputable sources varies but consensus seems to suggest that raising water to 100C will have killed all bacteria and viruses. Cysts are a little tougher and advice is to maintain 100 degrees C for one minute to be safe." (sorry haven't mastered quoting yet)...

This is a common misconception and incorrect. I'm an environmental scientist, my field is water, and have just spent the last year writing about the health risks posed to humans by cyanobacteria aka blue-green algae. Cyanobacterial toxins (which can potentially kill) are not removed through boiling or filtration. I can't comment on chemical sterilization methods but the best way to reduce exposure to cyanobacterial toxins is to take your water from a fast running, very cold, mountain stream.

Another example of how boiling is inadequate would be the bacteria found in boiling geysers.

[British Red]

Blue green algae are interesting. I believe the quote is correct in that boiling will in fact kill cyanobacteria, it will not however remove the chemical toxin that the bacteria has already created...in this way cyanobacterial toxins need to be treated as other chemical contaminents.

Would you agree with that (i.e. that cyanobacterial toxin is not alive)?

Red

[raspberryjam]

No boiling doesn't eliminate all strains of cyanobacteria particularly the micyrocystins. And as boiling results in cell abrupture some toxins are actually increased.

[British Red]

Thats fascinating - thanks for the info. I wish it was more widely available (e.g. in the WHO advice etc.)

[raspberryjam]

Sorry that should be microcystis not microcystins.
Yep I know but the data given in the WHO guidelines is from 1998, and its a badly researched area as most cases of illness resulting from cyanobacteria are inconclusive due to people being unable to directly attribute their symptoms with them being so wide ranging. My own study showed that people were unable to identify any potential hazard posed from cyanobacteria even when the amount present was in the highest value given by WHO in their guidelines for drinking water quality.

[raspberryjam]

Apologies I have misread...

You're right in that cyanobacteria can be destroyed by boiling however this can increase the toxins released particularly from microcystis...but to say that boiling at 100 degrees and in the case for cysts at least a minute is misleading, but you have pointed out 'for long enough time'...

lolol very sorry it's been a long long day

[Elines]

There is a device for testing whether or not water has been 'boiled' enough. You can find it at

http://www.solarcookers.org/catalog/...a905e68df85e2b

This is saying that you only need to pasteurise water to 65 degrees C for a short period for it to kill microbes, including E. coli, Rotaviruses, Giardia and the Hepatitis A virus. This might be really helpful when you are at altitude and cannot boil water at 100 degrees C. The device itself is very small and lightweight. The glass tube is about 1 inch long (I think).

[ged]

There is a device for testing whether or not water has been 'boiled' enough. ...

Nice find Chris, and not as expensive as sometimes things in this, er, neck of the woods can be. Any idea what it weighs?

Something like that could be handy if, say, you're very short of fuel. If not, I think I'd still opt for ten minutes at a rolling boil, just to be on the safe side.

[Elines]

hi Ged - re weight I'm pretty sure we are talking of grammes - I did actually buy one some years ago (never used though) as it was (then) so cheap but now can't find it

[Ogri the trog]

I'm pretty certain that I saw something very similar to that when researching through Cody Lundin's pages a few months ago - though I'm blowed if I can find it now. His was very simple and home-made - length of clear plastic tube, pellet of wax and a stainless steel washer - one end of the tube was sealed by flattening & heating, put the wax pellet inside the tube, put the washer over the tube and flatten & heat the open end - washer held in place by the flattenend ends. Maybe it had a cord for lifting it out as well but not sure now. In operation you arranged the wax to the top end and the washer to the bottom - when the wax melts and falls, its done!

Ogri the trog

[g4ghb]

a quick google turned up this - http://www.youtube.com/watch?v=YGWXD...eature=related how to make a wapi! - nice idea if you can get the wax.

[Elines]

Interesting to see how simple they are to make.

I would have thought that:

• given the low cost of buying one from Solar cookers
• the fact that the money goes to a good cause
• the difficulty of getting the correct materials economically (plus thin metal cable instead of fishing line so that a fire doesn't melt it)
• the importance of the device actually being made correctly and working to the spec

That it was best all round just to buy one - or maybe loads in a group buy (and as I already have one (somewhere) no I don't want to organise it!)

[Elines]

Nice find Chris, and not as expensive as sometimes things in this, er, neck of the woods can be. Any idea what it weighs?

Something like that could be handy if, say, you're very short of fuel. If not, I think I'd still opt for ten minutes at a rolling boil, just to be on the safe side.

Whilst looking for something else I found my WAPI (Water Pasteurisation Indicator). It weighs 4 grammes on the kitchen scales but that is with fishing line for attaching the weights. I will change this for wire, reweigh it and take a picture with a ruler included to give an idea of scale but if I can't do it tomorrow it will be a few days

[Elines]

OK - here is the WAPI as supplied to me a few years ago.



You can see that it has nylon fishing line attached to it to help you use it and get it out of the water to check it has been heated enough to pasteurize it. I think they used nylon line because its original use was when cooking with solar power rather than heating over a fire.

Nylon line is not so good when using a fire because it can/will melt. I intended to replace the line with metal wire but could not find any suitable. (I tried stripping a single cable that had lots of thinner wire in it but the individual wires kept snapping - so if anyone has any good ideas on how to find some wire about one foot long and the thickness of fishing line please let me know)

The instructions for use are:



and




The WAPI - even with wire instead of nylon line - is of negligible weight and could be helpful in an emergency. It may be of valuable routine use at high altitudes where the boiling point of water is below 100 degrees C (but I am not a scientist )

[leahcim]

water is a tricky subject but I like to find natural springs, which are pure sources. I drink tree saps like birch, sacymore, maple, hickory, walnut, basswood, etc. at certain times of the year. you be surprise what a turkey oven bag will do as a solar still that will hold up to 3 gallons and purify water about 1 gallon in 6 hours of direct sunlight after filtering with banada, or t shirt mixed with sand grasses, peppbles. Sawyer water filter is the best I owned, just dipp and drink. but if you camp in natural springs you can drink the water straight from the source, so look for them on maps. USGS has a web like to a google map that list almost ever watersource in America including springs and wells.

[MJM1]

Nylon line is not so good when using a fire because it can/will melt. I intended to replace the line with metal wire but could not find any suitable. (I tried stripping a single cable that had lots of thinner wire in it but the individual wires kept snapping - so if anyone has any good ideas on how to find some wire about one foot long and the thickness of fishing line please let me know)

Old guitar string?

[Elines]

Old guitar string?

Thanks - will keep an eye our for some

[ged]

...Nylon line is not so good when using a fire because it can/will melt. I intended to replace the line with metal wire but could not find any suitable. (I tried stripping a single cable that had lots of thinner wire in it but the individual wires kept snapping - so if anyone has any good ideas on how to find some wire about one foot long and the thickness of fishing line please let me know)...

Sorry Chris, only just seen this.

I'd think you might be better off with some chain. There are all sorts of very light chain in hardware shops but make sure it will take the weight by trying to break it before you trust your dinner to it!

Flexible wires are a bit of a problem. They can last for years at a bending radius something like ten or twenty times the diameter of the wire rope, but can break very quickly if repeatedly bent much more tightly than that. This is called metal 'fatigue' and is why wire ropes e.g. on cranes and boats always run over large diameter pulleys.

I have a lot of thin stainless stranded wire, you'd be welcome to a couple of feet of that if you want to give it a try, but I think chain has more going for it if you can work with it.

[Elines]

Ged - thanks - PM sent

[bronskimac]

What about Web-Tex Surviva-pure Survival Straw, in-line filter and canteen? http://www.web-tex.co.uk/index.php?a...productId=1447
Their marketing apearts to suggest that you can stick the straw into the most nasty puddle and drink clean safe water.
They mention "Cryptosporidium Giardia, Anthrax and many more harmful bacteria", no mention of viruses.

Sure I saw some similar kit from another manufacturer recently..

[Emdiesse]

Assuming you are not in any hurry (ie. Not dehydrated) would evaporation remove heavy metals, chemicals from the water?

[mrcharly]

It depends on the chemical - some will evaporate before the water, so you would end up concentrating them!

Boiling for a bit, then distilling would seem to be the way forward. The initial boiling drives off the low-boiling temp chemicals.

[Emdiesse]

It depends on the chemical - some will evaporate before the water, so you would end up concentrating them!

Boiling for a bit, then distilling would seem to be the way forward. The initial boiling drives off the low-boiling temp chemicals.

That makes sense, so if you have a litre of water to get it on a rolling boil to kill off the nasties and also chemicals that will boil lower and evaporate faster than water. Then after a few minutes of rolling boil start catching the steam.

[Greek1983]

I'll give my input. Read it a while ago somewhere in a Greek blog and translated in English:

How to purify really dirty water

1) Put the water into a clean container (plastic or metal) and leave it there for half an hour so as solid particles drop to bottom.

2) Then, take a clean cloth, fold it four times, and place it on top of another, clean metal or aluminium container.

3) Empty the dirty water to the clean container

4) Boil it for 1 minute.

5) Take a clean beer bottle. Fill 1/3 of it with chlorine and the 2/3 with water you previously boiled. Shake the bottle well and let it for half an hour. You now have made “light” chlorine.

6)Afterwards, for every 1 litre of boiled water put 3 drops of the “light” chlorine you previously made. Let it again for another half hour and then drink.

I was told but cannot confirm that if the water is full of chemical contaminants you redo the steps 1-2-3-4 and 6 again.

[British Red]

I suspect that there is a translation problem here.

Chlorine is a gas

Do you mean Sodium Hypochlorite (bleach)?

If so, adding bleach after boiling is fairly pointless - bleach will not kill anything that a rolling boil didn't kill

[Greek1983]

You're right, "bleach" is the correct one. My bad.

I haven't tried the above method so as to verify that it works. I guess bleach should be replaced with iodine or Betadine

[British Red]

Not so much.

Both chemical treatments and heat both act to kill micro organisms. In effect you are using two treatments where one will do. Neither will be effective on chemical contamination - really only activated charcoal works for that. Its certainly worth settling or filtering out all particles first as organisms can be shielded from the actions of heat or chemicals if contained within larger particles of soil or clay or even faeces in running water.

[Greek1983]

Indeed, whatever method you use, again you need a purification device. Good thing is after reading your introductory post on page 1 I can now learn alternative methods when not having tablets and/or the Lifesaver Bottle.