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Comment by mattkrause | Hacker News Reader

Also isn't the water....boiled for coffee and tea? Perhaps not enough to totally sterilize it, but it must help some.

I think to kill all bacteria you need to boil for several minutes. A typical tea kettle turns off immediately after reaching the boiling point. Coffee is a similar story I guess.

Right...to actually sterilize something, you have to hold it well above boiling. Autoclaves run at high pressure so they can get liquids up to 121C.

However, you don't need sterile food; you just need to ensure that there are sufficiently few bacteria that your body can deal with the rest. I would suspect boiling water (to make the coffee) and holding it hot (for serving) helps quite a bit with this, but I was wondering if anyone had some actual numbers.

I guess the question is exactly what's in the water.

Sterilizing river water calls for one minute at a rolling boil, which you won't get from a kettle. But something like beef, with a much more restricted threat, can be done down around 160F, and bringing your kettle to a boil should easily get you a few minutes above that line.

Not all tea brewings will, but I'm guessing "boil it and throw in tea" is more common on airplanes than a delicate, 165F green tea production.

So... it'd be nice to hear from a microbiologist about the specifics on this one. Regulators seem concerned, but that's about drinking it as tap water, which I wouldn't do.

I'm 99% sure that any boiling will kill nearly all germs in water. I don't have facts on hand, but I do remember that once you get above ~160F, nearly all germs are dead. So boiling water will definitely kill everything.

According to the CDC, at elevations above 6,500 feet, water needs to be boiled for three minutes to kill E. coli.

That's a pressure issue, though - low air pressure drops boiling temperature, so your water doesn't actually get as hot. Most commercial aircraft are pressurized to around 11psi, which is an elevation of ~3,500 feet.

It will kill the pathogens which cause vomiting and diarrhea: the article mentions e. coli, which the CDC[0] recommend 1 minute at boiling temperature to deactivate. I'd skip that and stop as soon as the water boiled.

Note that sterilization requires higher temperatures for longer periods, but it's not required for food products consumed by the general public. Some bacteria may survive the boiling process, but your stomach acid + immune system will destroy them.

[0]: https://www.cdc.gov/healthywater/drinking/private/wells/dise...

Good point! That's why posting on HN is so great, even if you're 99.9% correct, someone will always reply to tell you precisely how you are 0.1% wrong . Thanks for the link, I tried to find official sources online and had trouble.

To be clear, I think your original comment is just fabulous and you're 100% right.

I'm just curious since I know that controlling the level of E. coli contamination in milk is important from first-hand work on dairy farms, plus I know that pasteurization heats (not boils) the milk, and not for the ridiculous durations I see when searching online for "making water safe to drink".

Also, the relevant factor is not just temperature--it's a combination of time and temperature. For milk, you can do 1-2 seconds at 135C (UHT), 15 sec at 72C (HTST), or something like 20 min at 60C.

Boiling point reduces as pressure reduces.

Cruising altitude on a plane is roughly equivalent to air pressure at 1800-2400m, so using [1] that means water boils at around 93°C.

(If I had any familiarity with Fahrenheit, I wouldn't have bothered looking this up. 160°F = 70°C, and even on Everest water boils at a higher temperature.)

[1] http://docs.engineeringtoolbox.com/documents/1344/boiling_po...

> I'm 99% sure that any boiling will kill nearly all germs in water. I don't have facts on hand, but I do remember that once you get above ~160F, nearly all germs are dead. So boiling water will definitely kill everything.

Occasionally I find out that something that I thought / hoped / believed to be the case ... wasn't.

Killing 'nearly all germs' is good, but not really what you need when you may get sick or die from the kinds of germs that don't fit the 'nearly all' category.

Cryptosporidium and giardia (two things that Sydney residents became overly familiar with before our Olympic hosting) require a few minutes of rolling boil to kill. And the definition of 'rolling boil' becomes more onerous as you increase your altitude.

> I'm 99% sure that any boiling will kill nearly all germs in water.

CDC says a full minute of boiling (3 minutes for elevations greater than 6,500ft) to deal with (the problem strain of) E. coli in well water. Momentary boiling is not sufficient for safety.

https://www.cdc.gov/healthywater/drinking/private/wells/dise...

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