How long should you boil to purify?

abo4ster

abo4ster

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Aug 24, 2003
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Seeing a lot of different recommendations out there, so I thought I would pose the question. I know what I believe (trust), wanted to see what you thought and in the interest of education perhaps pass along valuable info. So...

How long should you boil water to purify?
 
There was a study done by, I believe it was Duke university, that said that one only needs to bring it to boiling. They point out the time that all those nasty germs are exposed to the heat as it reaches boiling, the short time it is actually boiling, then the time it takes to cool, as being more than enough time to kill even the nastiest of them.
 
I've heard 5min as the Golden Rule... But I do 10....THere are some forms of crypto sporidium that can withstand extremely high temperatures for a bit
 
It only needs to be brought to boiling in order to make most clear water safe to drink. If there is much junk in the water (suspended particulates etc.) Then it is a good idea to boil for a few extra minutes as a safety measure.
 
Have to agree with just bringing it to a boil...

http://www.princeton.edu/~oa/manual/water.shtml
"Boiling is the most certain way of killing all microorganisms. 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. To be extra safe, let the water boil rapidly for one minute, especially at higher altitudes since water boils at a lower temperature."
 
Apologies; my previous info was incorrect. As abo4ster pointed out, it was Princeton that did the study.
 
I have read as much as 20 minutes to kill spore-stage bacteria (i.e. protected and harder to kill) and that lower times are suggested because "who is going to wait 20 minutes?" I know folks who have traveled in many areas with questionable water sources (Rural India and South America) and swear by Grapefruit Seed Extract. Supposedly kills everything. Only addressing biological contamination.
 
From what I hear, all it needs to do is be brought to a boil. Don't quote me, as this may be wrong, but that is what I do and I am not dead yet.
 
Bring it to a boil, add a shot of cognac and all the bugs will die with a smile on their faces.
 
There is another (recent) thread on purifying water on here and it was linked to a site that shows the temperatures needed to kill parasites. Those temps are way below boiling point for water and the site(I think it was the CDC site) says that once water is boiling everything is dead.

I'm off to try and find that thread so I can link it up for you.

David

Here is the thread...



http://www.bladeforums.com/forums/showthread.php?t=653569

Here is the site...

http://www.cdc.gov/healthywater/drinking/travel/backcountry_water_treatment.html



Actually, once I got back to the thread I realized someone had linked the CDC site but that once I got on the site I found this info by searching the site.


Anyway according to the CDC boiling ( a rolling boil for 1 minute) kills everything but if you're over 2000 meters you need to boil for 3 minutes.

David
 
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All of the actual studies, some referred to here, state that by the time water reaches a rolling boil it has killed everything. If you want to boil it longer based on what you've heard or read there's certainly no harm in that (unless you don't like wasting fuel) but bringing it to a rolling boil is all that's necessary.
 
CSG-that's what I have always found to work. Once it starts boiling take it off the heat and it's good to drink. However, I was directly quoting what the CDC has on their website. My guess is that they added the one minute minimum to take the possibility of human error out of the situation.

David
 
if there is particles in it . get it to a rolling boil for 30 seconds..to a min.. that is what I was told by a few friends from the marines.
 
A minute of rolling boil seems to be the maximum required.

That said, if you're traveling through places with sketchy water, bring along a filter and some Pristine or Katadyn tablets. Boiling is fine, but it doesn't filter-out particulates and leaves you with boiling water - no fun when you're thirsty. The weight of the extra fuel is far more than a few Katadyn tablets or even a small filter [on an extended trip]. Filters get rid of bacteria and particulates, but don't handle viruses. Chemicals don't deal with particulates, but kill everything ... sometimes, with cold water, you need to wait a bit. I do most of my hiking/climbing in the mountains of the Pacific NW so clean water isn't an issue, but if you're dealing with nasty water, get a filter!
 
When boiling water at sealevel a short boil will do..
At higher levels water will start boiling at lower temperatures, and therefore need a bit more time..
 
Redpoint-a tip that may help a little.

If you need to filter out particles a peice of window screen works great, for very small particles a bandana ( or other cloth ) works good.

As far as the boiling water issue...after it boils put a lid on it and sit it in whatever your water source is. It'll cool down soon enough. Believe me, I've been in places that you didn't drink the water unless it was boiled (even if it was treated, you still boiled it).

About the only water treatment I'd trust as much as boiling would be reverse osmosis unfortunately the machines require a truck to tow them and they are not cheap at all.

David
 
Boiling is my preferred method. Sterilizes water and container. If you're using a fire, fuel is not an issue. Steripen runs a close second. 90 secs to purified water.
 
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