The Science of Water

[Andy woodsman]

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.

I teach the Duke of Edinburgh Gold Expeditions and for the first time in 30 years we had an outbreak of Crypto on one of the groups while in the Welsh Mountains, which caused the students to be ill for two complete weeks. This could have been because they failed to boil their water properly as instructed (they ran out of gas) and didn't use tablets, but it can also be picked up from the ground. Either way, they were very ill. The severity may also be because they were fairly young (16-18) and hadn't got any sort of immunity.

Like many others, I have used Millbank bags and boiling and have never had a problem - this year I spent two months on an expedition in the Amazon jungle and found this means very good - although people often forget that to get the best from a Millbank bag you need to brush it hard whilst it is wet on the outside with a stiff brush before it will give its best flow. We had to purify in excess of 150 ltrs per day for our team and used the largest milbank bags to remove sediment, and then aquatabs to purify it - this could then be used for cooking or drinking cold.

[jonajuna]

with regards the boiling point being lower at 8000 metres plus

other than the "brown lumpy" snow or the "yellow" snow, are there actually any bacteria or viruses at that altitude and constant, well below zero temps to worry about?

id have thought just heating the snow long enough to warm it so you dont lose body temps drinking ti would be adequate?

same for the polar ice caps would've thought?

[Steve M]

The Royal Geographical Society advises a rolling boil of five minutes at any altitude. Bacteria is still there at low temperature. You wouldn't want to heat it to body temperature only, since that's their ideal reproduction level.

[phill_ue]

For stagnant water you could consider digging a few yards away from the edge of the pool and getting below the water table. Bail out the first few fills of water to clear lumpy sediment out and then carefully scoop the water off as the fine particulate matter settles. Treat as water from other sources by filtering/treating with chemicals/boiling.

[hurplegrappers]

Excellent article Red. If ever there was a reason to sticky a thread then this is it. Very important subject.

Has anyone had any experience adapting one of these? :

Doulton® SLIM-LINE 2″×9¾″ Ceramic Filter Cartridges ULTRACARB™ Filter type

"DOULTON ULTRACARB (2×9.3/4in.) FILTER FEATURES:
The Doulton Ultra-Carb is a three stage cartridge combining the highly efficient properties of ceramic with the enhanced water treatment properties of activated carbon.

First Stage:
The first stage consists of DOULTON ULTRACARB ceramic which is manufactured to provide genuine sub-micron filtration. The cartridge reduces fine particulate matter, bacteria, cysts and turbidity.

Second Stage:
The incorporation of silver locked within the ceramic structure inhibits the growth of bacteria and gives enhanced bacteriostatic and self sterilizing properties.

Third Stage:
An inner core of activated carbon block which removes chlorine, VOC's and industrial solvents."

As it's for plumbing I suspect all the components would be reversed relying on water pressure to push upwards, hmmm problem..

EDIT : Also found this too Doulton HCP counter top water filter

May have similar issues.... Any ideas?

[hurplegrappers]

I've just bought one of these :

Platypus Cleanstream Gravity Filter System

I'll let you guys know how I get on with it.

[jonajuna]

The Royal Geographical Society advises a rolling boil of five minutes at any altitude. Bacteria is still there at low temperature. You wouldn't want to heat it to body temperature only, since that's their ideal reproduction level.

my point though Steve, at those sorts of altitudes, water "boils" at well below 100c, around 70c if i recall correct

but as the ambient temp at those heights is well below that which sustains life anyway, there 'should' be no bacterial or viral life there anyway which would need killing by boiling

in addition, the water sources at those (and much lower) heights would be snow, snow like rain should be as clean as you can get .......as long as not contaminated on the ground or failing through trees etc

its of note (for interest only, wont effect anyone, ever!) that there are several bacteria that actually thrive at well in excess of 100c, ok they do live on volcanic vents at the bottom of the ocean! but still :P

[AJB]

but as the ambient temp at those heights is well below that which sustains life anyway

What kind of temperatures are they and is there really no bacteria/viral life at those temperatures?

Just curious

[jonajuna]

What kind of temperatures are they and is there really no bacteria/viral life at those temperatures?

Just curious

the average annual ambient temp at the summit of everest is < -40c. this can lower with wind chill factor

at anything over 5000m, the ambient temp is < -17c



your freezer at home is at -18c

very few things will live at that temperature simply because all life is water-based at the base level of intracellular fluid, when a fluid freezes, it expands, cell walls cannot expand much, so the cell explodes and will die

human tissue freezes at -4c and we are quite hardy in comparison to simple beings such as bacteria especially as we have the ability to generate heat through our metabolic processes

some life will "suspend" at below freezing and reanimate upon warming. not aware that any of those bacteria/viruses that effect the human gastric tract do so. but they may

also bear in mind that you need a certain level of bacteria/viral load to actually cause you harm (this is the principle upon which refrigeration works... the temp isnt below freezing but low enough to keep any bacteria present below a level that causes food to spoil) so even if there are a small amount present, and melting the snow reanimates them, they would then require a food stuff and the temperatures to remain high enough for long enough for bacterial growth to happen to the point it becomes "infective"

viruses require a host cell for replication so must infect first

bear in mind, snow comes from the sky, the process of water evaporation, condensation and precipitation is a big natural distillation process. and we already know that distillation cleans water of everything bar chemical contamination

but! never eat the yellow snow :P


of course, drinking melted river/pond/puddle ice (especially at low altitudes where life would normal thrive in the "normal" milder conditions) without boiling/purifying it first will put you at risk as the bacterial/viral load my have been so high previously, that enough remains to cause infection. especially if that water is murky as the soil/dirt particles could act as insulation for the bacteria/viruses present

[AJB]

Very interesting thank you for your efforts

Ok, Questions!

Why does it start to warm up above 17km?

So are you saying a perfectly freash at time of freazing chicken breast could be eaten "raw" after freazing as all the bacteria would have been killed at -18C?

[jonajuna]

it warms at that hieght as thats the upper limit of the troposphere. this atmospheric layer is heated principally by reflection of heat from the earth, thus the higher you go, the less heat.... above this layer it gets "warmer as you go higher until you hit the final layers of the atmosphere which get progressively colder again until you hit "space" where its either very hot or very cold, depending on whether you are shadowed from the sun or not

as for chicken, yes your theroy should stand assuming that the fresh chicken was free of bacteria, which it is likely not, unless grown in a bacteria free environment with futuristic chicken sanitary arrangements

my chickens, poo all over the place, are not vaccinated for salmonella (most small animals carry this unless vaccinated) or anything else, eat bugs and grubs and anything else they think might be edible including droppings on occassions!

[AJB]

Ok, that’s what I assumed, even though it still seems counterintuitive. As to the hypothetical chicken (they don’t lay well but do have lovely plumage) you said all the bacteria would be killed by the growth of ice crystals rupturing their cell’s, so what does it matter about the numbers prior to freezing?

[British Red]

I would be highly cautious of the idea that freezing will kill all microbial life forms

Microbes can survive for many thousands of years in ice far colder than the average household freezer. For those who would like to read a little more on the science of this, please click here

http://www.newscientist.com/article/...000-years.html

Red

[jonajuna]

Ok, that’s what I assumed, even though it still seems counterintuitive. As to the hypothetical chicken (they don’t lay well but do have lovely plumage) you said all the bacteria would be killed by the growth of ice crystals rupturing their cell’s, so what does it matter about the numbers prior to freezing?

I would be highly cautious of the idea that freezing will kill all microbial life forms

Microbes can survive for many thousands of years in ice far colder than the average household freezer. For those who would like to read a little more on the science of this, please click here

http://www.newscientist.com/article/...000-years.html

Red

i never said freezing would kill all bacteria

some life will "suspend" at below freezing and reanimate upon warming. not aware that any of those bacteria/viruses that effect the human gastric tract do so. but they may

freeze dried food is safe for consumption. and bacterial growth will only happen once above freezing in previously frozen food

so....

for it to remain safe for human consumption it would need to undergo and instant defrost and consumption or undergo the normally quite slow process in a sterile environment, else as the temperature rises, you would have food, temperature and moisture conditions that woudl allow bacterial growth to flourish and youd get ill

of course you can miss out the thawing process and cook frozen chicken perfectly safely dispite the mythology surrounding that action

.......paused for a while......

ok, ive gone and googled for some "facts" Salmonella apparently is not killed by domestic freezing. i cannot find the temperature at which it would die (it will exist, even if its absolute zero K) so unless your chicken is 100% Salmonella free, then it would still have active Salmonella post freezing/defrost

however, chickens are not water, and chickens certainly do not live at alitiudes higher than several thousand meteres

my point was, at altittudes in excess of 5000m, all water is (likely) to be in the form of frozen precipitate aka snow which not only will be very cold thus at least inhibiting bacterial growth, but will be devoid of bacteria (subject to not be contimated on way down (no trees to do that)) or after settling on the ground (no animals other than humans to do that) as it has been through the big distillation process in the sky

so, why would snow need to be boiled at such altitudes and is it possible to achieve the temps necessary for a 100c rolling boil when water boils at around 70c at that hieght? surely water would boil off before getting anywhere near 100c?

all academic of course as i wont be going there

[AJB]

Sorry to have dragged you into this - I assumed that when you said "very few things will live at that temperature simply because all life is water-based at the base level of intracellular fluid, when a fluid freezes, it expands, cell walls cannot expand much, so the cell explodes and will die" you were referring to bacteria and viruses (as they need a cellular host) – that’s what I also found counterintuitive just from general knowledge.

A very interesting hijacking of the thread though

[jonajuna]

yes, most bacteria (not all) will die if at below freezing. they are cellular beings and will pop. at "normal" temps, they will divide and replicate. no host needed

viruses need a host cell to replicate as they are not cells in their own right... a weird little thing. viruses can happily (assuming the right kind) infect bacteria and thus replicate

it is interesting as you say, but the chicken thing was a tangent, one we are both at fault for

maybe another thread? "the science of chickens"? LOL

[Steve M]

so, why would snow need to be boiled at such altitudes and is it possible to achieve the temps necessary for a 100c rolling boil when water boils at around 70c at that hieght? surely water would boil off before getting anywhere near 100c?

Water boils at around 69 (close enough to 70) degrees on top of Everest. Water will not get to 100 degrees at this altitude, it'll have vaporized by then. The RGS say rolling boil, not a temperature. The same time at this reduced temperature is fine because the nature, state and quantity of bacteria is different to down here.

Alternatively, 30 minutes at 66 degrees will pasturise water.

[CaptainBeaky]

Excellent article, Red

Couple of points...

High pH (i.e. alkaline, not acid) will reduce the efficiency of halogens (chlorine/bromine/iodine), due to the equilibrium between the hypohalite ion and hypohalous acid species.
[Chlorine in aqueous solution exists as a mixture of hypochlorous acid and sodium hypochlorite - your bog-standard bleach - the hypochlorous acid is the more efficient disinfectant, by a factor of about 20, but the equilibrium goes rapidly towards hypochlorite as pH rises (becomes alkaline)]
Chlorine is affected far more than bromine or iodine at normal pH ranges - chlorine efficiency starts to fall once you go over a pH of about 6.5. Bromine is OK up to about 8.0, and iodine is good for pH8.5 - 9.0 - which you won't reach in any sensibly potable water

Secondly - Legionella pneumophila - (and the other Legionella species if you want to be really pedantic)...

Yes, you will find it in puddles etc - it is found almost everywhere.

No, you are NOT likely to contract legionellosis from drinking water with Legionella spp in it

Legionellosis is contracted by breathing in small droplets (i.e. aerosols) of water containing high levels of Legionella bacteria.
Water from a pond or river is extremely unlikely to have the required high levels of Legionellae, because the water won't be warm enough (30C plus) for the legionellae to multiply sufficiently. If the water is warm enough, I would suggest you will have other problems with it which will eclipse any hazard from Legionellosis
You are also very unlikely to generate the required aerosol of small droplets, unles you put your collected water through a pumped shower.

Summary - don't worry about Legionnaires disease when you're out in the woods.

Hmm... this wasn't intended to be a lecture

Incidentally, yes, I am a chemist, and I've been earning a crust in the water treatment industry for a couple of decades...

[ged]

I just wonder if an already very informative thread could usefully be extended by mentioning things like a hole in the ground, a piece of polythene, a tin can and a few small rocks; or the sponge that I use to wipe the infernal condensation from the inside of my single-skinned tent (which I only bought because it was being cleared after a tent show for a fiver).

To keep it on topic, the science in this case is mainly about the dew point, but you could stretch that in all sorts of interesting directions.

We could get into containers, and other means of taming an otherwise unruly substance.

We could weigh up the uses to which water lends itself, like hot water bottles!

We could work on perspiration, its properties and its avoidance.

We could even, if we really wanted to, consider ways of absorbing water that don't involve drinking it.

Any takers?

[snelgrave101]

excellent info Cheers , on the subject of water a few effervescant vitamin c tablets in your kit makes up a lovely drink
and keeps your vitamin levels topped up .

[Ray Britton]

ged said:

We could even, if we really wanted to, consider ways of absorbing water that don't involve drinking it.

Hmmm, do you fancy a bit of rectal infusion?

We could talk about it, but then it would upset all the posters who have gone to SO much trouble to tell us how to sterilise our water!

Of course if you really wanted to get obtuse on this, then we could get into ways to boil water at lower atmospheric pressures....But at sea level!!

Have any of you out there ever boiled water at less than 100 degrees C at sea level?.....I know its hardly practical, but is an interesting thing to see

[CaptainBeaky]

Of course if you really wanted to get obtuse on this, then we could get into ways to boil water at lower atmospheric pressures....But at sea level!!

Have any of you out there ever boiled water at less than 100 degrees C at sea level?.....I know its hardly practical, but is an interesting thing to see

Yes, I have, but in a lab, crystallising out some stuff which didn't like anything over 65C. Had to get it down to under 100mmHg to avoid decomposing the product when evaporating off the water...

Not really something you can do out in the woods (unless your rucksack is a lot bigger than mine )

[Ray Britton]

Hi Captain.

There is a slightly easier way (well, for that read: massively easier way).
Pop your very hot water into a wine bottle, and fit a wine vacuum sealer onto it. As you then pump out the air, the pressure will drop and the water will start to boil. Once it stops boiling, just pumped out some more air, and the water will boil again.
Thus you can have water that has never reached 100 degrees, but has been boiled enough to sterilize it.

Why would I need to get into a situation where I can only heat but not boil my water? I hear you ask?.
You could perhaps of found an old wine bottle, and an old fizzy drinks bottle.....You could heat the water in the fizzy drinks bottle on the embers of your fire until the water is nearly boiling (not forgetting to keep the fizzy bottle lid away from the ashes),, then decant it into the wine bottle.........As for finding the vacuum keeper, just make something else up

[CaptainBeaky]

Ray:
Unfortunately, it's temperature, not evaporation that does the sterilisation, which is why autoclaves operate at high pressure - to increase the temperature achievable in the chamber.
Reducing the pressure so that water boils at a lower temperature also reduces the sterilising effect.

[ged]

Getting back to science:

http://www.bbc.co.uk/news/technology-10858815

[Ray Britton]

Hi captain Beaky.
Yep, I knew that thanks lol, hence my comedy stance of the wine bottle thing, and the smiley at the end.
I was just throwing in an obtuse way to do something, which can be amusing to see (and done at sea level), rather than being a pedant. Having been loosely involved with water (and potable water) for twenty years, I have learned that to be over pedantic can lead to confusion lol.......Such as pointing out that it is not steam that comes from the top of a kettle...Or from a steam iron lol, or that central heating boilers don't boil, or that radiators mainly convect, not radiate. Another fun experiment is showing that water does not always find its own self level (which goes against what is taught at school), hence gravity hot water heating systems.

On the other hand, if I were in a cheeky mood, I would point out that evaporation is actually an excellent way to obtain pure potable water (but not strictly sterilized), and can be done at quite low temperatures too when used with a solar still, rather than the traditional type of still. The good side is whether you are using a still, boiling or an autoclave as you rightly point out, its all SCIENCE based, and all good fun.

I have to admit, your evaporation comment did make me chuckle (as it does take a while to sterilize water at 65 degrees lol)

Uh oh, thread drift again lol Smacks wrist, and sits in naughty corner.

[CaptainBeaky]

Hi Ray
Dunno - being over-pedantic and confusing can be quite amusing at times The difference between evaporation and boiling is always a good one with which to tease the unwary

And definitely don't start on gravity-fed HWS - the number of hours spent grinding my teeth over airlocked hot water systems in the last 20-something years... Pressurised every time - please...

[Ray Britton]

Captain Beaky.

How right you are over air locks!
It gets worse when you try to explain to the customer that their water is somewhere up in the pipework, but isn't coming down to play.........Which is always followed by them stating 'but water always goes to the lowest level'

Maybe in school experiments, but not in the real world lol

[Steve M]

So, I've mostly been reading about bacterial spores. Any thoughts on managing those bad boys in a survival context?

[ashes1627]

Good post, thanks for this! Great work!