The answers at How long does water need to be boiled for to kill all bacteria / viruses? indicates that boiling water kills bacteria & viruses. But boiling does not remove any chemical contaminates that might be present. Neurotoxins are not "alive" so they can't be killed, though some like botulinum toxin are denatured by heat.

Historically the practice of boiling vinegared wine in lead pans to sweeten it was problematic. This was not due to a change, but rather leaching from the container (lead pan) to the fluid.

Are their any contaminates that might be present in water, that would become more toxic when boiled in modern containers?

  • 3
    very interesting question. Though, if any do exist I'd say that boiling is still your best decontamination option. Don't cut off your nose despite your face!
    – user2766
    Nov 20, 2015 at 10:45
  • 2
    Agreed, pretty dang interesting question. While not a 'contaminant' but to expand on this a bit... in many ways boiling down salt water could have a negative effect... it can result in a higher level of salt within a lesser amount of water, which is why RO or steaming tend to be the safest ways to desalinate salt water. This could be a good question for the water lab folks at MSR.
    – Abela
    Nov 20, 2015 at 13:06
  • Interesting yes, and it is too bad there are no real answers to the question. The answer from @Escoce is the closest, but it is essentially just "yes" with no elaboration.
    – Loduwijk
    Apr 28, 2017 at 22:05

2 Answers 2


There are essentially three categories here:

1) water contaminates made safer by boiling.

2) water contaminates unchanged by boiling.

3) water contaminates made more dangerous by boiling.

In case one, boiling works by killing biological organisms, rendering them unable to infect you.

In case two, there are toxins that won't be affected by the heat.

  • Heavy metals
  • toxins already secreted by organisms (like botulism)
  • Gas/oil

In case three, it would be elements made worse by the heating or, in some cases concentration of the water if left to boil too long.

  • Certain plastics break down under heat
  • Salt (as pointed out by Abela)

So there are SOME cases, but it is likely not a major problem.

  • heavy metals will be concentrated if we boil water.
    – Joel
    Dec 1, 2015 at 3:45

The answer is yes, potentially some contaminants could become more toxic compounds when subjected to heat. However the chances of you camping in such a location is rather remote, because places that get contaminated thusly are usually off limits.

  • Not sure this is going to be the best answer. As @Abela pointed out in the comment to the question, Sea water is a great example and I am pretty sure most of the sea shores in the world are not closed to camping, hiking, or other outdoors activities. Nov 20, 2015 at 16:26
  • 1
    Salt isn't exactly toxic, and sea water already is too salty, it would clearly become saltier as the water boiled away. You'd be pretty hard pressed to drink it after that first sip, and that first sip won't hurt you. You'd have to choose and have the discipline to drink something your own body is telling you to spit out.
    – Escoce
    Nov 20, 2015 at 16:28
  • A look at the The 25 Most Polluted Places On Earth... well they mostly look populated... Nov 20, 2015 at 16:29

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