How long to boil water?

19-3ben

19-3ben

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The other day I was thinking about boiling water to kill pathogens in a bushcraft/camp/survival type situation. Some of the common wisdom I've heard when it comes to this is to boil the water for ten minutes. I'm wondering if that's actually really necessary and why? We're talking about microbes here. It's not like a large animal where it would take a bunch of time for their core temps to rise and kill them.

So given that we're talking about microscopic stuff that'll heat up at roughly the same time as the water in which it is floating, once that river water in your pot gets to that magical temp of 165°F, the stuff inside ought to be dead anyway. Letting it get to boiling is really, in my mind, just a way to make sure you surpassed the 165° mark, and maybe for a bit of overkill because you really don't want to take chances. The last thing I want when out in the woods is a case of giardia, but I'd think this would be taken care of once the water hits the boiling point. Remember that the water also doesn't instantly boil. It's going have some time between hitting 165° until it hits 212°, and then time again at high temps until it cools enough to drink.

So let's talk about this. Once it's already hit boiling point, is there really a benefit to letting it boil for 10 minutes? So far I have let it boil for ten minutes just because it's "the common wisdom" and I don't want GI upset to ruin a camping trip, but I wonder if it's necessary. I profess no expertise on this, and genuinely would be interested in feedback even if it's to say "Ben you're an idiot and you're going to give yourself a case of the sheeeits while far from toilets and TP."

What say you?
 
By the time you've reached about 160 degrees F for 30 seconds, you've killed most germs. By the time you reach 212 degrees, you've killed all the germs.
CDC recommends boiling for one minute.

Do I feel more comfortable boiling a little longer? yeah, I do, but that's just because I think an extra minute or two is worth it just to make sure the water reaches a homogeneous 212.
 
EngrSorenson said:
By the time you've reached about 160 degrees F for 30 seconds, you've killed most germs. By the time you reach 212 degrees, you've killed all the germs.
CDC recommends boiling for one minute.

Do I feel more comfortable boiling a little longer? yeah, I do, but that's just because I think an extra minute or two is worth it just to make sure the water reaches a homogeneous 212.
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I don't much care for the CDC anymore but the above sounds perfect, 212 F = 100 C, as we learned in school. Note that you might extend the minute a little longer at higher altitudes.
 
OK I'm glad I wasn't totally off base here. Intuitively I just can't wrap my head around a need for a 10 minute boil, but I do understand how I'd lose vital water through evaporation by boiling for that long. I only see down sides here.
 
It depends on altitude. One minute of a rolling boil is sufficient. If above 5000 feet. it's 3 minutes. Pretty sure if I was at around 4000 feet I'd go for longer than a minute. But I don't know an exact altitude to start adding time. But I err on the side of caution, and just add some extra time if I'm up higher.
 
boiling-points-of-water-1328760-FINAL-c9c25739167d4722926f2caf69fbae7a.gif
 
On the other hand, it takes forever to cook when you are high ... and saving gas is higher priority sometimes, while snow is abundant.
 
Out here in the southwest we have to be a bit cautious of the Cyanobacteria that exists in some streams. It’s also called blue-green algae and the stuff can cause severe health issues or death. Boiling won’t make this water safe to consume. The toxins are not destroyed and boiling ruptures the bacteria and even more toxins are mixed into the water. Total bummer but something to consider. I’ve always tried to find a seep in canyon country. That water travels through a lot of material before it issues out of the rocks again. It can be a challenge to harvest. Once I climbed a 30’ wet scree pile and balanced on the top edge capturing a little stream that took a few minutes to fill my gallon bag. In the ensuing drought who knows if the seeps are reliable.

Can’t tell for sure but this stuff might be widespread. Stay safe.
 
SwiftDream said:
Out here in the southwest we have to be a bit cautious of the Cyanobacteria that exists in some streams. It’s also called blue-green algae and the stuff can cause severe health issues or death. Boiling won’t make this water safe to consume. The toxins are not destroyed and boiling ruptures the bacteria and even more toxins are mixed into the water. Total bummer but something to consider. I’ve always tried to find a seep in canyon country. That water travels through a lot of material before it issues out of the rocks again. It can be a challenge to harvest. Once I climbed a 30’ wet scree pile and balanced on the top edge capturing a little stream that took a few minutes to fill my gallon bag. In the ensuing drought who knows if the seeps are reliable.

Can’t tell for sure but this stuff might be widespread. Stay safe.
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Not just in the SW. Anywhere you have warm water it can happen, which is why the algal blooms are a concern. I test drinking water for these cyanotoxins, and I see it occasionally in surface water in warmer weather. Some of these cyanotoxins have an LD50 of only 30-50 ug/Kg, compare this to the potassium cyanide LD50 of about 5 mg/Kg, which means these cyanotoxins are about 100 times as toxic as potassium cyanide. It doesn't take much.
 
lambertiana said:
Not just in the SW. Anywhere you have warm water it can happen, which is why the algal blooms are a concern. I test drinking water for these cyanotoxins, and I see it occasionally in surface water in warmer weather. Some of these cyanotoxins have an LD50 of only 30-50 ug/Kg, compare this to the potassium cyanide LD50 of about 5 mg/Kg, which means these cyanotoxins are about 100 times as toxic as potassium cyanide. It doesn't take much.
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Wow, that’s good info. A few years ago there a woman went missing 12 days in Zion and said she’d drank the Virgin river water. The sheriff said the toxic water from the Virgin River for 12 days would likely have killed her. I think they may have doubted her story. A dog died earlier from playing in the river. The story put this stuff on my radar.

Would a normal filter be safe or would one need a serious purifier? I like the idea of sterilizing but the potholes and small containments sure have a lot growing in them so it’s hard to say what is safe after simple boiling.
 
SwiftDream said:
Wow, that’s good info. A few years ago there a woman went missing 12 days in Zion and said she’d drank the Virgin river water. The sheriff said the toxic water from the Virgin River for 12 days would likely have killed her. I think they may have doubted her story. A dog died earlier from playing in the river. The story put this stuff on my radar.

Would a normal filter be safe or would one need a serious purifier? I like the idea of sterilizing but the potholes and small containments sure have a lot growing in them so it’s hard to say what is safe after simple boiling.
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There is no filter or purifier on the market with pores small enough to stop these cyanotoxins. You might be able to filter the cyanobacteria, but any free toxins would pass through. The toxins are pretty polar molecules so I don't know how effective activated carbon would be. That would be something to investigate. Look for carbon effectiveness for microcystins and anatoxin for a start.
 
I don't think that even reverse osmosis is rated to remove cyanotoxin. It can happen pretty much anywhere, so it's always worth knowing the local area and its conditions. I know that I've seen warnings for it from central Alberta to South East Queensland.
For those who are wondering about changes in guidelines, a lot of it is "dummy proofing" the process and a chain of people adding more padding to the number. It takes far more energy to boil water once it hits just under the boiling point, so anywhere near sea level if fuel was a concern I'd generally be happy with just before the boil to purify the water (source depending). Also keep in mind that organizations like the CDC are massive, and so advice published should always be taken on its own merits, think what you want about other info, but be aware of how many layers of people some info might have gone through before it gets to the public. Some info especially that going to professionals and not wide public consumption will be far more "accurate" but have a far lower range of forgiveness for mistakes. Part of this is because "clean, purified, and sterilized" sound like synonyms to most, but mean very different things in a lab.
 
lambertiana said:
Not just in the SW. Anywhere you have warm water it can happen, which is why the algal blooms are a concern. I test drinking water for these cyanotoxins, and I see it occasionally in surface water in warmer weather. Some of these cyanotoxins have an LD50 of only 30-50 ug/Kg, compare this to the potassium cyanide LD50 of about 5 mg/Kg, which means these cyanotoxins are about 100 times as toxic as potassium cyanide. It doesn't take much.
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Yikes!
What’s this now?
I’m guessing this doesn’t occur in CA because I’ve been backpacking my entire life and never heard of it.
You mentioned a test - is this for personal use or is that your job?What do you use?
 
scdub said:
Yikes!
What’s this now?
I’m guessing this doesn’t occur in CA because I’ve been backpacking my entire life and never heard of it.
You mentioned a test - is this for personal use or is that your job?What do you use?
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It's in California. I have tested a few sources in California that had microcystins. A dog died a few years ago after drinking stagnant water near Fresno. But I doubt you will see it in the Sierra high country because the water doesn't get warm enough for long enough. I drink water completely untreated and unfiltered in the Sierra high country all the time
 
Makes sense. Seems like it’s us desert people who’ll have the biggest possibility. I recently bought a larger water bottle for the trail.
 
It actually depends on your elevation. Atmospheric pressure varies by elevation, and the pressure affects the boiling point of water.

The boiling point of water is 100 degrees Celsius at 1 atmosphere of pressure. You can raise or lower the temperature of the boiling point by increasing or decreasing the air pressure above the water.

See, it's the high temperature which kills pathogens in water. It's not the fact that the water is boiling. It's just the fact that it's hot that matters. The boiling is just a useful indication of the fact that the water is hot enough to kill the viruses and bacteria in it.

The higher the temperature of the water is, the faster the germs are killed. So if you are at a low elevation where the boiling point is close to 100 degrees Celsius, it only takes one minute of boiling to kill all the germs. But if your elevation is high, then the boiling temperature of the water is lower, so it will take a longer boiling time to kill everything. I've heard that it can take up to 3 minutes at high elevations, so that's how long I would boil the water just to be on the safe side. If you wanted to be super-duper extra mega safe, you could boil for 5 minutes. 10 minutes is probably extreme overkill.
 
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