View Full Version : KMnO4 Toxcitity
I found the following abstracts while searching for info on the toxicity levels of KMnO4 (Potassium Permanganate). I have used, and will continue to use, iodine (Potable Aqua™ tablets or 2% Tincture of Iodine solution) for my main water purification method. I do carry KMnO4 as a backup in my PSK, taped inside the pocket of my canteens, and in various knife-based kits.
My problem: I got a “D” in chemistry in high school and my medical knowledge is mainly gleaned from trips to the ER. Does anyone here have any idea what the actual dosage of potassium permanganate is if you add three or four sugar grain-sized crystals to one liter of water? Apparently from the following abstracts a dosage of 5 – 10 grams can be lethal. The recommended dosage for water purification is far below this but how far?
What is the comparative health risk of ingesting a water purification dosage of KMnO4 as opposed to the standard dosages of Iodine used for the same purpose (5 to 10 drops of 2% Iodine solution per liter)? Mac
KmnO4 Toxicity
IPA COPYRIGHT: ASHP A case of corrosive burns to the mouth, esophagus and trachea in a 3-yr-old boy who ingested 5-10 g of potassium permanganate (I) is presented. The mouth was washed repeatedly with water. He was given 2 glasses of milk. Laryngoscopy revealed edema of his upper airway. He was intubated to prevent upper airway obstruction secondary to progression of the edema. The child received an intravenous administration every 6 h of ampicillin 50 mg/kg and hydrocortisone 4 mg/kg. The laryngeal edema resolved and he was extubated 3 days later. A follow up esophagoscopy at 7 days showed normal mucosa and he was discharged. A plasma manganese level performed on day 4 was 4.1 mcg/l, one month later this had fallen to 1.5 mcg/l.
The pathogenesis of the systematic toxic effects of potassium-permanganate (7722647) (KMnO4) was examined, based on the case history of a suicidal ingestion. The patient was admitted to the hospital 1 hour after ingestion of about 5 to 10 grams of KMnO4 crystals, with hands, lips and oropharynx stained dark brown. She was treated with activated charcoal and antibiotics. Alanine-amino-transferase (ALT) and lactate-dehydrogenase (LD) levels increased significantly by day two. Acute hepatic necrosis and progressive cardiovascular failure developed. N-acetyl-cysteine was administered 48 hours after ingestion. ALT and LD levels peaked at day three. On day six she died of complications arising from hepatic, renal, cardiovascular, and respiratory failures. Postmortem examinations revealed significantly higher whole blood and tissue manganese (7439965) concentrations, relative to a control autopsy. The authors conclude that oxidizing free radicals generated by the permanganate ion are predominantly toxic to the liver and kidneys, perhaps due to the high blood flow through these organs. They recommend that N-acetyl-cysteine, a reducing agent, be administered as soon as possible after KMnO4 ingestion.
IPA COPYRIGHT: ASHP A case of a 66-yr-old man who ingested 125 ml of an 8% solution of potassium permanganate (10 gm) over a 4 wk period is reported. Neurological and gastrointestinal symptoms are discussed. Treatment with pentetate calcium trisodium decreased serum levels and increased urine excretion of manganese. Nine months after poisoning, the first sign of progressive Parkinson disease become evident.
dave750gixer
03-03-2005, 13:04
Cant give you an exact value as the KMnO4 in my lab is much finer than sugar sized so I put roughly that amount in a vial and weighed it. Weight about 5 mg thats 0.005 g. So for a severely bad dose of 5 g you are at 0.1 % of that. So to ingest the equivalent of the 5-10 g dose reported you would have to drink somewhere in the region of 1000 - 2000 litres of treated water. Not too likely as the water itself would be fatal a long way before 1000 litres.
Hope that puts it into perspective. Even if you used 10 times the recomended amount to purify the water you would still need to drink 100 litres of water and at 10 times the dose the colour of the solution would be a big warning sign that you got it horribly wrong.
RovingArcher
03-03-2005, 16:30
Since reading about KMn04 on the ETS site and how many actually used it to purify water, I was surprised to read later, just how toxic it really is and of course, then questioned the sanity of those that carry it. I didn't follow it up anymore, because there was no way I was going to carry it with me.
Pict, please correct me if I'm wrong, but is the last paragraph of your quote hinting that the patients development of progressive Parkinsons disease is related to his taking KMn04?
RA,
I didn’t read the full articles. Apparently they thought the KMnO4 could have possibly been a factor in the early onset of Parkinsons or they wouldn’t have included it in the summary.
The quote that concerns me is “The authors conclude that oxidizing free radicals generated by the permanganate ion are predominantly toxic to the liver and kidneys, perhaps due to the high blood flow through these organs.” Now I’m not a pathologist and won’t pretend to really understand what an “oxidizing free radical” does, but on a cellular level they are toxic to the liver and kidneys.
This makes sense. After all, we are introducing the stuff to water to kill off single-celled organisms. I once had ants invade my cat’s food. I sprayed it with ant killer and a few minutes later my cat was chowing-down (sorry, tucking-in) on the sprayed food. The 1-800 number lady asked how much the cat weighed and how much she ate. Her explanation made sense. “The ant spray is designed to kill-off animals that weigh a fraction of a gram, your cat will be just fine.”
Unfortunately, the cat lived. Later she fell off a five-story building to a stone floor below. She survived that too so I wonder if my example is really useful at all. My cat could probably crawl through a chipper and come out fine. Mac
Dave,
Thanks for the reply. Toxic and fatal is different than just toxic and "bad for you". What do oxidizing free radicals do in the body? Mac
Wildpacker
04-03-2005, 00:29
When I really need the artificial stuff I just use puritabs and don't lose sleep. I know people even older than me who've been using them for years, and I know of people younger than me who died in car accidents. Whatever you do, something is going to kill you. The way things are going it will probably be your supermarket or the tap water.
Most times in the wild I just filter and boil and hope for the best.
Most times in the wild I just filter and boil and hope for the best.
In the wild, away from the affects of farmers that's by far the best way :wink:
ChrisKavanaugh
04-03-2005, 07:06
I think the interest at ETS is a result of it being carved in stone just below solar sills in outdoor literature. Yes, it can be used to make fire, sterilize water, disinfect a wound and act as a distress marker dye on water or snow. It is also caustic to skin, has long been abandoned as a wound treatment and is just plain difficult to purchase and store. Tropical fish fanciers still use it, and indeed that became our stateside source for the stuff. It is also a ingredient in various improvised devises and likely to draw attention in some instances. Again, using it is like making fire with an ice lens. It's a great stunt to impress people with your $200 weekend vision quest/ survival seminar. My version comes in a box of 250 for @ $1 USD. I boil my water over one of the 3 distress fires I started and clean any wounds with that water (dilution negates pollution.)
Chris,
KMnO4 is still widely used in South America for treating skin infections. I think that's mainly because it is so cheap. They sell it in foil flats divided into 10 sections for about $.25 USD. Each section holds 10mg of KMnO4. It is a very convenient size to include in a PSK, it's available at any pharmacy, and costs next to nothing. Like I said though. I prefer to use iodine. Mac
You can get this stuff at Boots over the counter, no prescription required, in a fine granulated form for about 99p.
If people have used it for years, then I don't have a real problem using it myself. As previously mentioned, something is always being discovered as being bad for you, hardly a week goes by when the news doesn't tell us about the next cancer causing food stuff - Worcestershire Sauce?!!!
If we paid a lot of attention, we'd be living off boiled water and twig soup. Oh yeah, some of us do!! :lol:
Walkabout
04-03-2005, 12:01
What do oxidizing free radicals do in the body? Mac
If I remember from chemistry A-Level A free radical is a compound that has been split leaving each part with one lone electron. Since the electrons like to be in nice neat pairs each part is now really reactive. So they find something to go and steal an electron off (oxidising means to lose electrons). that means they can basically attack anything they come in to contact with. This is what CFCs do in the atmosphere. The sunlight splits them into free radicals and they go and mess up a load of ozone molecules.
dave750gixer
04-03-2005, 12:40
If I remember from chemistry A-Level A free radical is a compound that has been split leaving each part with one lone electron. Since the electrons like to be in nice neat pairs each part is now really reactive. So they find something to go and steal an electron off (oxidising means to lose electrons). that means they can basically attack anything they come in to contact with. This is what CFCs do in the atmosphere. The sunlight splits them into free radicals and they go and mess up a load of ozone molecules.
Good explanation. Mine would have been too scientifically correct and therefore completely pointless as no one would know what it meant. You actually got the meaning about perfect for understanding.
What you have to remember is that everything is harmfull in a high enough dose even water and oxygen. People have died from drinking too much water and oxygen above a certain % or partial pressure becomes harmful. Heck if you dive both the nitrogen and the oxygen you breathe in can kill you if you go deep enough. For the examples given with people actually surviving ingestion of 5-10 g there are a lot of things we carry which would be fatal at a dose below this. If I remember correctly paracetamol (for example) can be fatal at about 3.2 g but no one suggests that paracetamol is therefore too dangerous to use as a painkiller (dose of 500 mg - fatal dose is 64 times this whereas the discussion above has a KMnO4 dose of 5 mg with the fatal dose example being 1000 times this. For everything there has to be a risk analysis based on likely dose and route. Just looking up the end result in massive overdoses doesnt really tell us anything about the actual risks in use.
Although I do have to point out that like everything else these values are generalisations. Some individuals may show severe effects of poisoning at much lower doses that other people. DO NOT exceed doses of pharmaceuticals etc given on the pack, they are designed for your protection. Also many materials can have severe health implications well short of a dose which would lead to death. Also just beacuse one person survived 5 g of material doesnt mean you will. Moderators feel free to delete this post if you think the overdose discusion is too risky.
I prefer to filter then boil water. Next choice is iodine. For survival rather than bushcraft I also carry KMnO4. I have never actually used it to purify water but have used it as a fungicide and as a fire starter. I would use it as a snow marker but have never had to. I would use it to purify water but have never had to. I carry it since it is multipurpose. I probably would rather use an iodine tablet in water as an emergency antiseptic but again would use it for that if I had to as well. The risks of KMnO4 as a water purifier are vastly overstated IMHO. The doses we are talking about are tiny. I would rekon that in a survival situation I would be much more likely to kill myself by getting food preparation or selection wrong than I would be in sterilising my water with too much permanganate.
In the UK the purple stuff (easier to spell) is sold in 25g pots, so there is an OD opportunity, but you wouldn't use it all at once. If your local pharmacist doesn't have it, he can get it within two days.
I'm no expert, but I believe the reason it is so useful for firelighting and purification is precisely because it is an oxidising agent. (Also the reason it can used in "improvised devices.)
As a matter of interest, can anyone here provide a comparison with the toxicity of iodine? That's not exactly healthy stuff either.
dave750gixer
04-03-2005, 15:08
I'm no expert, but I believe the reason it is so useful for firelighting and purification is precisely because it is an oxidising agent. (Also the reason it can used in "improvised devices.)
bit of confusion here. loss of electrons is oxidation and gain of electrons is reduction. these are terms from electrochemistry originally from behavior of metals particularly in corosion but later applied to all materials. A free radical is short of an electron and it therefore takes this electron from another atom thus oxidising it. It is this ability to form free radicals that makes permanganate useful in water purification.
KMnO4 is also referred to as an oxidising agent. But in this case the word oxidising has a different meaning. Here it is used to mean a material which can act as a source of oxygen. it is this effect that has a bearing on improvised devices and on firelighting
purple stuff just happens to be able to have the word oxidising applied to it with both meanings
confused yet :o):
dave750gixer
04-03-2005, 15:37
As a matter of interest, can anyone here provide a comparison with the toxicity of iodine? That's not exactly healthy stuff either.
iodine - Toxic - may be fatal if swallowed or inhaled. Corrosive, causes burns. Harmful by inhalation and through skin absorption. UK OES short-term 1 mg/m3 (0.1 ppm). Readily absorbed through skin. Very destructive of mucous membranes and upper respiratory tract, eyes and skin. Severe irritant. Sublimes at room temperature to yield dangerous levels of vapour. May cause sensitization. May cause damage to the unborn child.
ORL-HMN LDLO 28 mg kg-1 , UNR-MAN LDLO 29 mg kg-1
The last two bits are the important ones. These values are the lowest recorded level casuing death in man (usually obtained from suicide or industrial accident and more meaningful than animal values where available note that these two are specifically recorded as human and man).
ORL is oral, UNR is dose route unrecorded. The doses are in mg (1000 mg = 1 g) per kilo of body weight of the patient so 28 mg/kg is 1.4 g for a 50 kg person.
Similarly for
KMnO4 - Harmful if swallowed. Irritant. Readily absorbed through skin.
ORL-WMN LDLO 100 mg kg-1
as above but a woman for a 50 kg body weight dose would be 5 g
Excellent info Dave. Nicely done.
I think KMnO4's biggest risk is getting a small crystal in the eye or inhaling some of the dust. Oral ingestion of a toxic dose would be relatively difficult for someone who was trying to purify water...it could be done but certainly not something I would expect from anyone who remotely understood the intended dilution. However a tiny crystal on your finger rubbed in the eye could cause some major damage.
KMnO4 is promoted as a multi-purpose tool, sort of like looking for the "one" ideal knife you can end up with a tool that is not actually very good at anything. There are much better water purification chemicals and means, there are much better firestarters, there are much better snow markers etc, so to carry potassium permanganate as your only option for these purposes would be folly.
I do have a tiny vial of KMnO4 in a PSK I put together a few years back, but I consider it a last resort tool...a backup to my backups rather than a first option.
Thanks for the info Dave especially the interpretation.
So, to be symplistic about this, iodine is far more reactive and more toxic than the purple stuff. I still like to carry the purple stuff.
Adding a bit more common sense, who takes a bottle of neet iodine to go camping? :rolmao: Puritabs are already in a safe dose, so little chance of od, but not as versatile (or as colourful). :hurra:
ChrisKavanaugh
04-03-2005, 17:06
In the end everyone should be familiar with all the options, methods ( arcane and current) anyway; the snow lens, Manhatten Island bowdrills et al :o): You never know when Mr Murphy will wash you ashore with a kit of your least liked compass, firestarter, hollow handled CHICOM survival bowie and MREs of liver and brussels sprouts in Bernais sauce :yikes: As for " backups for backups?" My old CPO in the C.G. said that is like using a .38 SPL revolver to backup a .375 H&h rifle. Don't lose the rifle! :Crazy_071
A LITTLE OFF TOPIC
All this talk of pot. perm., etc.,..just *how* dirty *is*our water?? Do we really need to purify it, poisoning everything? I have quite clear memories of drinking from burns (still do it) and lochs as a child. Remember, Scotswoman here...contract with my maker, rained on at least twice a day :-) ....part of the delight was that the waters did taste different.
I'm not being wilfully stupid here, but genuinely interested. I eat fruits and berries and leaves and roots straight from the plant, and my hands certainly aren't usually that clean when I'm outdoors.
Waters that have human effluent or farmyard runoffs (that's kinda banned now anyway) I would naturally avoid, but just what buggits are commonly, or even likely to be, a problem in the UK?
Cheers,
Toddy (Who's fed up to her back teeth sewing 16th century kit and is enjoying a cuppa and a treacle scone :-) I have a carrier of linen and wool scraps if anyone wants some to play around with for charcloth)
Over here one option is to carry a bottle containing neat iodine. Polar Pure or its hand done options takes about a gram of elemental iodine in a 2 oz bottle, you add water to the bottle and an iodine saturated solution forms above the crystals. Then depending upon the bottle temperature, a certain volume of the supernatant is added to your water bottle to purify. It is possible to decant an iodine crystal so the Polar Pure product includes a mesh screen but the hand done ones you just have to be careful.
This neat iodine method has its primary advantage in that you can treat hundreds of litres of water with it vs the few litres you would get with tablets of iodine or chlorine.
As in all things the need to disinfect water is completely location dependent. Some places I go Giardia is the main issue. Filtration or boiling is usually a better option with these large cysts. So you just have to know why you may or may not want to use certain methods. Iodine, chlorine, permanganate, filtration, UV, boiling, nothing are all options...each with their own difficulties and efficacies.
ChrisKavanaugh
04-03-2005, 18:10
A few years ago Los Angeles completed a major sewage treatment facility. The engineer in charge turned a tap, filled a glass of sparkling clear water and offered it to the news reporter. She looked over the holding ponds of brown effluent, wrinkled her nose and refused. Worldwide, virtually 100% of our waters are now contaminated; agriculture runoff from chemical fertilizers, fungicides, pesticides and animal waste or offal, chemical contaminates from heavy industry, mercury poisoning in South America from gold mining operations, old fashioned critters from Mother Nature ( dysentary is the #1 killer of children worldwide) and deliberate poisoning of wells in fratricidal civil wars. I was in the arctic and came upon a beautifull pink patch of snow. Closer observation was not so pretty. It was the frozen jetsum from a passing airliner :yikes: A tourist to Mexico bought a alcoholic beverage and went into shock. The icecubes were contaminated and she died within hours. In some countries bottled water containers are artfully refilled with local sources and resold. I'm sure 99% of these horrors don't happen in Scotland and knowing your local environment, growing up with it's local flora as part of your personal chemistry makes it relatively safe. But if you travel, remember Wednesday Addam's admonition " Be afraid, be V-E-R-Y afraid."
This is a post I made about 3 years ago at ETS. I updated the links to the Assembly of Life Sciences National Research Council publications which are really a very good, but long discussion, on drinking water. There are now multiple volumes, but in a quick look, Volume 2 is still the one to start with.
ETS also has numerous more recent discussions on water treatment, many on potassium permanganate and many on other methods.
I more or less still go with what I wrote 3 years ago....
So here goes:
Warning…long discussion follows. Get a cup of Coffee first.
Potassium Permanganate (KMnO4) seems to have one of the desired attributes that make its inclusion in a PSK highly desirable. Many authors have cited multiple uses for Potassium Permanganate including: water purification, topical antiseptic/antifungal wash, fire starting, and signaling (snow dye). Like all other items that are selected for small PSK’s it is worthwhile to evaluate the efficacy of Potassium Permanganate for each of these reported uses.
Water Treatment
The primary role of Potassium Permanganate in a PSK seems to be as a water disinfectant. It has much greater storage stability than iodine or chlorine tablets and does not need special packaging within the kit. A common screw top plastic vial is suitable, as the chemical must only be protected from moisture and is readily available for use. It does not chemically degrade like iodine or chlorine tablets upon exposure to air. It does not sublime producing a very corrosive and staining gas and eat everything it touches in the kit. Very small amounts of Potassium Permanganate are also reported to be effective for water purification. This makes a small vial go a long way for water treatment.
However, the primary question is one of effectiveness against the water pathogens expected. The best source I have been able to find is the 1980 drinking water report from the Assembly of Life Sciences National Research Council. This report is long, but compares several methods of water treatment commonly used for municipal water systems. Potassium Permanganate is fairly commonly used in municipal treatment systems to kill algae and remove iron and manganese. It is not commonly used to kill pathogens, and is not considered effective for this large-scale use.
The first two links are to this report. The third link is to a much shorter review of various water treatment methods.
Drinking Water and Health
Volume 2
SAFE DRINKING Water COMMITTEE
Board on Toxicology and Environmental Health Hazards
Assembly of Life Sciences National Research Council
NATIONAL ACADEMY PRESS Washington, D.C. 1980
http://www.nap.edu/books/0309029317/html/index.html
More Drinking water publications can be found here:
http://www.nap.edu/books/0309038979/html/related.html
AntiFungal/Antiseptic
Here it seems that Potassium Permanganate may have some utility. Making a moderately pink to red solution in water to treat fungal infections, wash hands, wash fruits and vegetables may have some utility. Trekking groups make reference to using KMnO4 solutions to treat locally procured produce. I could find no references that determined the value of such uses but what could it hurt.
Fire-Starting
Now here is a unique and fun use for this chemical. Mixed equally with sugar and sparked initiates violent oxidation of the sugar. According to David Alloway this reaction can also be initiated by friction with a knife or ground with a dry piece of wood. Potassium Permanganate simply mixed with glycerin also reacts to start a fire. Glycerin is a common constituent of brake fluid so this may be available in an aircraft or automobile accident.
Signaling
Using Potassium Permanganate to stain snow is a novel use. I can attest to the staining properties of very small amount of this chemical to bathroom grout. Fill your vials in the garage as the nearly invisible dust goes everywhere and the addition of water produces a very deep purple color.
Chemical Safety
KMnO4 is a strong oxidizer and the dry powder should not be allowed to make contact with the eyes or mucus membranes. Because the chemical is usually supplied as a fine powder, inhalation or contact with the eyes and mouth is possible. Solutions present much less risk.
My Opinion
I do not think that Potassium Permanganate is effective enough to be my primary water purification method. I carry iodine tablets (Potable Aqua, full-unopened bottle), and will fall back on KMnO4 if required with the understanding that it is probably not going to be very effective.
Treatment of fungal infections, washing wounds or food items does not seem to rank high on my likely use of this chemical.
I have used Potassium Permanganate and Glycerin to initiate fire in a lab setting. I do not carry glycerin and may not be able to locate it in an emergency, so I am going to practice the dry friction methods and sparking methods. I see some utility here even though I could probably prepare dry tinder and start a fire with the sparking device I carry without using KMnO4. Potassium Permanganate is an alternate to the 4 other fire-starting methods I carry (ferro rod, butane lighter, strike anywhere and LifeBoat matches along with some tinder). KMnO4 serves more as emergency tinder with some special reactive characteristics.
Visible and effective signals on snow may require more of this chemical than I am currently carrying. However it does produce an unusual color that contrasts well with snow, so this use does have practical value. The hardest part is to sprinkle the chemical lightly enough to produce a large signal.
So What
In an objective evaluation of the likely uses for my PSK shelter, fire and water are the 3 primary needs for which I carry multiple redundant devices. Potassium Permanganate makes the cut as an included item in my PSK as it serves as backup to my iodine treatment for water purification and as novel maybe useful fire-starting tinder. I carry two 0.5mL plastic cryovials one of KMnO4 and one of sugar. Violent oxidation of sugar is just too cool to not have as an option. It still comes down to the fun of building a PSK.
If you have read this far, thanks.
I take the point of the last three posts, and your information is genuinely happily received, but I'd like to re-iterate my question.
Is ordinary, running water, not from an area subject to human sewerage or silage runoff, likely to be harmful? Or if it is, what's in it that's going to give me grief? I suppose I'd better qualify that by adding; in an area of cool temperate rainfall like the UK.
Cheers,
Toddy
innocent bystander
04-03-2005, 18:42
Signaling
Using Potassium Permanganate to stain snow is a novel use. I can attest to the staining properties of very small amount of this chemical to bathroom grout. Fill your vials in the garage as the nearly invisible dust goes everywhere and the addition of water produces a very deep purple color.
.
:wave: I can testify to that - i spilt a few grains on the floor at work, and the poor chap who cleans the floor had to contend with a purple floor for weeks afterwards. Just couldn't get rid of it :rolmao:
There cant be that many places left in the uk where you could guarantee there isn't something in the water, short of the higlands and similar unfarmable places can there ?
Toddy,
That is just too open a question. Only local information and practice can answer that.
I can say that I have drunk flowing waters from places I walked in the past without any ill effects. However these same pristine waters now cannot be drunk without significant risk of Giardia. Things have changed over the years but the water still looks the same. Only local information gave me this insite and I no longer drink these waters without filtration. This example is from high elevation in Montana...there are no farms on this watershed it is a defined Wilderness...however there are, and have been humans, and horses in here for a long time...somehow this watershed was contaminated with Giardia and the resident animals and human visitors keep it contaminated.
My guess is that there are many places that surface water can be consumed with no treatment, but you really cannot tell. Once when I was a kid we were hiking and stopped at a stream crossing and tanked up, filled our canteen and then proceeded up the trail. Right around the stream bend there was a dead elk laying in the water....blown up huge. We dumped the water in our canteens and filled them above the elk :o): No effects....back then we never treated or filtered water.
Great stuff Dave :You_Rock_
[QUOTE=Schwert]Toddy,
That is just too open a question. Only local information and practice can answer that.
Again I do take your point, but what *are* we likely to come across that may cause us grief from the wild water.
We don't get elk, but sheep have a horrible propensity for drowning themselves so we watch for those. Gardia is supposedly very rare here, having usually been brought in from abroad and seems to be more a swimming pool and communal washing facilities problem. Shrimps I just filter out, but I don't think they're carrying anything noxious anyway. I don't drink where the are ducks around, so what else is there?
Maybe this ought to be on another thread?
Any Mods about to decide please? :?:
Cheers,
Toddy
In a general overview water contaminates can be:
Biological---viruses, bacteria, protozoa and
Chemical---heavy metals or pesticides etc.
If a flowing stream is visited by animals of any sort, birds, livestock, deer, beaver, whatever then it will probably contain some concentration of biological organisms from their gut. These are common in all waters and illness is generally dependent upon the concentration and type of these contaminants. Fecal coliforms are probably the bacteria of most interest. They will be present in nearly all waters which are visited by livestock or game.
A high mountain stream rapidly flowing from snow melt or rain runoff will probably be more dilute in these things than a stagnant pool, but just because the stream is flowing strongly does not mean it did not flow through a field of sheep dung just around the bend.
Other organisms of interest would be Giardia, protozoa with major effects on our gut, and the weird organisms that are common in tropical zones like liver flukes and other nasty things. In Scotland, my guess (guess only mind you) is that fecal coliforms would be of interest and while we can get sick if exposed to enough of these or some of the very nasty ones we carry plenty of them around everyday without any issues. There is one strain of coliform (e coli 0157) that has been responsible for death or debilitating illness from improperly cooked food contaminated with cow feces. This has also been found in waters.
Take a look at this site:
http://www.ecy.wa.gov/programs/wq/plants/management/joysmanual/streamcoliforms.html
They explain fecal coliforms a bit and show naturally occuring concentrations. Note that the Cedar river supplies water to where I live.
This Environmental Protection Agency report on coliforms is also useful
http://www.epa.gov/safewater/ecoli.html
Chemical contaminants can be found in waters both due to natural occurrence and man-made disturbance or intentional disposal. So waters that have flowed through old mine tailings may be high is certain metals or waste products from the mine itself. Mercury, arsenic, lead, etc or from waste ponds etc that were used in the reduction of the ore to a metal.
Application of fertilizers herbicides or pesticides can also contaminate water from runoff or intentional misuse.
For the bushcrafter, water purification is generally concerned with removal or destruction of the biological contaminants via boiling, filtration or chemicals. Chemical contaminates are not generally removed unless a filtration system is used that incorporates an active carbon filter.
This is a good overview of water issues applicable to backcountry, particularily Giardia which according to this article was probably introduced to the backcountry by man and then sustained in the wildlife that live there.
http://gorp.away.com/gorp/health/wtrflfaq.htm
I think that if you are taking water from a natural source, sterilisation in one way or another has to be a priority. When I lived in Plymstock, just outside of Plymouth, as a child, I used to drink water straight from a stream on the outskirts of town. I drank from where the water was flowing over some stones, which agitates the water and gives it that white frothed up look. I have always taken my water from such a feature, there is less sediment and the like in there. I never suffered any stomach bugs when doing this.
Nowadays, I boil the water taken from such a source, as I am normally going to have a brew anyway. I also carry puritabs, and as previously mentioned, the purple stuff with all intentions of using it if I have to.
I don't know of any particular nastys in British waters, apart from Leptospirosis, which is apparently present in most British waterways and can seriously spoil your day, and various types of algae. Sometimes signs are put up warning of the presence of dangerous algae.
I think with the various methods of making water safe to drink open to us, we would be folly not to use them. Remeber: Safety first, fun later!