# how effective is boiling water to purify it for drinking **URL:** \ **Category:** Factual Questions\ **Created:** [July 10, 2003, 2:16am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377 "2003-07-10T02:16:57Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![The\_Calculus\_of\_Logic](https://avatars.discourse-cdn.com/v4/letter/t/aeb1de/32.png) [@The\_Calculus\_of\_Logic](https://boards.straightdope.com/u/The_Calculus_of_Logic)\ **Post date:** [July 10, 2003, 2:16am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/1 "2003-07-10T02:16:57Z")
What all drinking problems will boiling water solve? I think it will turn saltwater into freshwater (im not sure on this), i know it will kill bacteria & viruses. So what other uses does boiling offer? What about impediments like chlorine, dirt or carbon, will boiling help with those. ---
**Author:** ![etgaw1](https://avatars.discourse-cdn.com/v4/letter/e/ed655f/32.png) [@etgaw1](https://boards.straightdope.com/u/etgaw1)\ **Post date:** [July 10, 2003, 2:21am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/2 "2003-07-10T02:21:45Z")
Boiling water will not turn salt water into fresh water, if anything it will concentrate the salt more. because water is evaporating ans salt is staying. All boiling does is kill micro orgnainsms; bacteia, viruses, parasites. Anything else will stay there. Of course if you are boiling your water you are most worried about the things that will make you sick fast, ususally those are microorganisms. etgaw1 ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [July 10, 2003, 2:30am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/3 "2003-07-10T02:30:11Z")
OTOH, if you boil water, collect the steam and allow it to condense, not only have you killed off any microorganisms, but but you’ve got fresh, clean, pure water with no dissolved solids, like salt. This process is called distillation. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 10, 2003, 2:32am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/4 "2003-07-10T02:32:31Z")
Well, technically, you can distill water by boiling it, which will leave it pretty pure. ---
**Author:** ![Rabid\_Squirrel](https://avatars.discourse-cdn.com/v4/letter/r/e0b2c6/32.png) [@Rabid\_Squirrel](https://boards.straightdope.com/u/Rabid_Squirrel)\ **Post date:** [July 10, 2003, 2:45am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/5 "2003-07-10T02:45:20Z")
> [@](#): > > - From Finagle\* > Well, technically, you can distill water by boiling it, which will leave it pretty pure. In order to do distillation, you have to boil it and then condense the vapours. Just boiling it isn’t distillation. If you screw up your distillation, it’s possible you’ll keep the organics/hydrocarbons in the water. Most of them should evaporate off at room temperature, but you might not get rid of higher molc weight stuff like benzene. I haven’t done microbiology for yonks, but aren’t viruses deactivated in water?. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [July 10, 2003, 2:55am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/6 "2003-07-10T02:55:30Z")
Boiling will destroy most microorganisms, in particular, [Giardia](http://www.doh.wa.gov/Topics/giardia.htm) and [Cryptosporidium](http://www.doh.wa.gov/Topics/crypto.htm). Some viruses, as well as bacterial and eukaryotic spores are resistant to heat but AFAIK these do not usually constitute a health risk. Boiling will not remove toxic metals, tannins, suspended clay, or any number of nasty chemicals. Precipitation, filtration, ion-exchange, will each remove some of these substances, but distillation is the most universally effective treatment. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [July 10, 2003, 8:29am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/7 "2003-07-10T08:29:53Z")
Some friends and I just returned from a camping trip, where we boiled glacier river water due to the bacterial concerns **Squink** mentions. Boiling will only _concentrate_ the other nasties mentioned though. I have a hard time with my Dad with this. He likes to boil the water he tops up the car battery with; I’ve explained that this is nothing like distilled water, in fact the reverse, but he likes doing it anyways. 🙂 ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [July 10, 2003, 11:38am UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/8 "2003-07-10T11:38:36Z")
One other thing that boiling will do nothing for is prions. They are not denatured until the temperature reaches several hundred degrees C. So watch out for mad cows bathing in your river. ---
**Author:** ![casdave](https://avatars.discourse-cdn.com/v4/letter/c/c6cbf5/32.png) [@casdave](https://boards.straightdope.com/u/casdave)\ **Post date:** [July 10, 2003, 5:12pm UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/9 "2003-07-10T17:12:00Z")
If you can increase the pressure you will raise the boiling point, this shortens sterilisation times dramatically. High temperature steam is used in autoclaves in hospitals extensively. ---
**Author:** ![Capt.Ridley\_s\_Shooting\_Party](https://avatars.discourse-cdn.com/v4/letter/c/cc9497/32.png) [@Capt.Ridley\_s\_Shooting\_Party](https://boards.straightdope.com/u/Capt.Ridley_s_Shooting_Party)\ **Post date:** [July 10, 2003, 5:28pm UTC](https://boards.straightdope.com/t/how-effective-is-boiling-water-to-purify-it-for-drinking/187377/10 "2003-07-10T17:28:29Z")
I’ve just returned from a camping trip, also. We bought some special tablets from the local chemists, they were about £5 ($8?) for 50 tablets. They contain small amounts of silver, and when left in the water for around 2 hours per litre, purify it ready for drinking. In the past we have also used liquid drops, which included chlorine, IIRC. However, if you get the concentration of the drops slightly wrong, you end up with swimming pool water ☹