Purifying Water

[pict]

Water is gtg once it boils. From some published material you would think they were trying to stew a chicken. Mac

 

[Don Rearic]

I wish they had them little aluminum flats of PP up here and they were available, of course.

 

[HikingMano]

Everything dies before boiling, but if we get it to a rolling boil, we can be sure.

Interesting table here on temperatures to kill nasties: http://www.ziemia.org/sodis.php

F = C x 1.8 + 32 so 60C = 140 F. Water boils at 212 F or 100 C.

Water is gtg once it boils. From some published material you would think they were trying to stew a chicken. Mac

That's right, with all the cell culture work and primary cell isolation I do in lab, things get pretty messed up if you vary the temp even a little beyond 37C. At least for mammalian cells. I don't think even the bacterium Thermus aquaticus, known for its resistance to high temps, can survive 100C.

However some bacteria like Clostridium botulinum (causes botulism, often found in soil, water, and mishandled food) produce spores that can survive boiling at 1atm (sea level). The spores are heat-activated IIRC and would actually thrive in 100C water because all other competing bacteria would be eliminated. That's why if we want something really sterile in lab, we autoclave it (temps reach above 100C). I believe that's also the reason behind pressure-cooking? But my guess is the chances of you running into C. botulinum are slim, depending on locale.



ETA:

Nm, I guess it's actually the toxin produced by the bacteria that is dangerous, and the toxin itself seems to be eliminated by boiling. From CDC:

Because the botulism toxin is destroyed by high temperatures, persons who eat home-canned foods should consider boiling the food for 10 minutes before eating it to ensure safety.

 

[Thomas Linton]

That's right, with all the cell culture work and primary cell isolation I do in lab, things get pretty messed up if you vary the temp even a little beyond 37C. At least for mammalian cells. I don't think even the bacterium Thermus aquaticus, known for its resistance to high temps, can survive 100C.

However some bacteria like Clostridium botulinum (causes botulism, often found in soil, water, and mishandled food) produce spores that can survive boiling at 1atm (sea level). The spores are heat-activated IIRC and would actually thrive in 100C water because all other competing bacteria would be eliminated. That's why if we want something really sterile in lab, we autoclave it (temps reach above 100C). I believe that's also the reason behind pressure-cooking? But my guess is the chances of you running into C. botulinum are slim, depending on locale.



ETA:

Nm, I guess it's actually the toxin produced by the bacteria that is dangerous, and the toxin itself seems to be eliminated by boiling. From CDC:

Good to know.

Have we had cases of botulism from drinking water? I know the spores are found in the soil. (So when eating dirt, boil for ten minutes. )

 

[Ramm9]

I wish they had them little aluminum flats of PP up here and they were available, of course.

I packed it in a drinking straw and sealed it the same way you would for Vaseline cotton balls.

 

[HikingMano]

Good to know.

Have we had cases of botulism from drinking water? I know the spores are found in the soil. (So when eating dirt, boil for ten minutes. )

That's a very good question. Quick googling yielded little; I don't think there have been any documented cases of botulism from natural drinking water. CDC put this up:

In the United States, an average of 145 cases are reported each year. Of these, approximately 15% are foodborne, 65% are infant botulism, and 20% are wound. Adult intestinal colonization and iatrogenic botulism also occur, but rarely. Outbreaks of foodborne botulism involving two or more persons occur most years and usually caused by eating contaminated home-canned foods. The number of cases of foodborne and infant botulism has changed little in recent years, but wound botulism has increased because of the use of black-tar heroin, especially in California.

I think in a natural environment, drinking boiled water containing spores likely won't result in anything (haha, so much for my cautionary note ). But using boiled water contaminated with spores to wash a wound could be a problem. Or say, using boiled water to hydrate your backpacking food and then eating the left overs later, after the bacteria get busy in the new nutrient rich environment. Like I said, chances are slim, and I'd drink boiled water straight away unless it came from a stagnant nasty pond with dead animals in it, but I'll stick to the chemicals after filtering/boiling if it's possible.

An interesting aside, I did find this study: "Elimination of botulinum neurotoxin (BoNT) type B from drinking water by small-scale (personal-use) water purification devices and detection of BoNT in water samples.". But apparently it's geared towards the recent evaluation of Botulism as a potential weapon in bioterrorism. Seems to be up there with Anthrax (http://www.ncbi.nlm.nih.gov/pubmed/18406986 , http://www.ncbi.nlm.nih.gov/pubmed/11209178 , http://www.ncbi.nlm.nih.gov/pubmed/16762741). I think the idea there is putting the toxin into an aerosol form, or probably less efficient/feasible but conceivable, poisoning municipal water supplies directly.

 

[Don Rearic]

Notes to self: Boil dirt before ingesting, home-canned foods are not as safe as once thought (B.S.) and lay off the California black-tar heroin.

 

[HikingMano]

Notes to self: Boil dirt before ingesting, home-canned foods are not as safe as once thought (B.S.) and lay off the California black-tar heroin.

Haha!

 

[glamdring]

I've read several sources about how long you should boil water before it is safe to drink and it seems that the length of time varies with the author. The time amount gos from point of rolling boil to 7 minutes. It seems to me that logic would dictate that once a rolling boil is obtained that everything should be dead, but you might as well err on the side of caution and boil 7 minutes.

 

[beef]

But water can't get any hotter than 100C right? at least in a standard pot. After that it just evaporates. Boiling water is the same temperature at a rolling boil as it is after 7 mins of boiling, correct?
I suspect that the advice about boiling for X minutes is just to ensure that the water is definitely boiling, as some people may not understand what a rolling boil looks like.

 

[ADD]

But water can't get any hotter than 100C right? at least in a standard pot. After that it just evaporates. Boiling water is the same temperature at a rolling boil as it is after 7 mins of boiling, correct?
I suspect that the advice about boiling for X minutes is just to ensure that the water is definitely boiling, as some people may not understand what a rolling boil looks like.

Yep boil is boil.

I suspect the rolling definition part ensures complete circulation and the extended times covers the author's arse for the novice...