# Hot Tub Question **URL:** \ **Category:** Factual Questions\ **Created:** [October 23, 2005, 9:37pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560 "2005-10-23T21:37:53Z")\ **Posts on this page:** 16\ **Page:** 2
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [October 24, 2005, 11:20pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/21 "2005-10-24T23:20:37Z")
> [@Xema](#): > > I once heard a guy claim that an effective way to keep a hot tub germ-free would be to occasionally raise the temperature to something like 140F and hold it there for several hours. This would, he said, pretty well eliminate the need for any chemical treatment. > > Naturally, he had no cite, and I can’t seem to find one either. Leaving out the fact that few if any hot tubs can reach that sort of temperature, is there anything to this? As far as I know, few if any hot tubs can reach 140. That’s hot enough to seriously maim or kill people. Besides, lots of bacteria love that sort of temperature. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [October 24, 2005, 11:28pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/22 "2005-10-24T23:28:40Z")
> [@Qadgop the Mercotan](#): > > few if any hot tubs can reach 140. That’s hot enough to seriously maim or kill people. Certainly - you’d need some sort of way to ensure that no one tries to get in while the tub is on its “self-clean” cycle (as with an oven). > [@](#): > > Besides, lots of bacteria love that sort of temperature. The same bacteria that cause problems at 104 degrees? If so, the idea is of no value. ---
**Author:** ![outside\_artist](https://avatars.discourse-cdn.com/v4/letter/o/7993a0/32.png) [@outside\_artist](https://boards.straightdope.com/u/outside_artist)\ **Post date:** [October 24, 2005, 11:44pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/23 "2005-10-24T23:44:31Z")
😃😃😃😃😃😃😃 I’m Getting a Hot Tub! I’m Getting a Hot tub! ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [October 25, 2005, 4:05am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/24 "2005-10-25T04:05:59Z")
> [@Qadgop the Mercotan](#): > > As far as I know, few if any hot tubs can reach 140. That’s hot enough to seriously maim or kill people. Hijack question: I know that egg white coagulates near 140. Does anyone know the coagulation temperature of semen? ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [October 25, 2005, 7:28am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/25 "2005-10-25T07:28:29Z")
> [@yoyodyne](#): > > Hijack question: I know that egg white coagulates near 140. Does anyone know the coagulation temperature of semen? You would have to ask **mangeorge**. 140F is the USDA minimum temperature under which all pathogens are killed. However, I believe you have to hold it there for at least 1/2 an hour. At higher temperatures, you can sterilise it in less time. ---
**Author:** ![Waterman](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Waterman](https://boards.straightdope.com/u/Waterman)\ **Post date:** [October 25, 2005, 8:32am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/26 "2005-10-25T08:32:53Z")
> [@Shalmanese](#): > > You would have to ask **mangeorge**. > > 140F is the USDA minimum temperature under which all pathogens are killed. However, I believe you have to hold it there for at least 1/2 an hour. At higher temperatures, you can sterilise it in less time. If this is true then why does the USDA still recommend cooking pork to an internal temperature of 160-degrees F? ---
**Author:** ![Waterman](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Waterman](https://boards.straightdope.com/u/Waterman)\ **Post date:** [October 25, 2005, 8:47am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/27 "2005-10-25T08:47:02Z")
> [@Dishfunctional](#): > > We drain, clean and re-fill our spa every fall, before the weather gets too chilly. It gets its heaviest use in winter, so that’s when the water is most “fresh”. > > Having said that, the water is actually being changed out continuously, since some is always being lost due to evaporation - more so in winter, since we stay in longer. Filling the tub back up adds “new” water, plus maintaining the proper chemical balance, keeping the filters clean, quickly purging critters that fly or fall in uninvited, and running the ozonator have proved to be more than adequate in maintaining a clean spa, in my experience. > > And if you’re just not big on the whole maintenance thing, it really helps to shower off before jumping in, especially on hot, dusty days. Dried skin and microscopic particulates trapped in body oils are by far the largest source of contamination in any spa. Bad reasoning here - evaporation only allows for water vapor to escape, the dissolved inorganic (sodium, sulfate, hardness, alkalinity, etc.) constituents in the water plus the inorganic additives that you use for treatment will just continue to concentrate until it finally start getting either or both soft or scale on your wetted surfaces. To maintain the concentration of dissolved constituents at a reasonable level it is recommended to drain off some of the water on a regular basis and then replace that with fresh water. One of the reasons (see below for another) that most chlorine and bromine compounds that are used for treatment are organic is because they will not add any dissolved constituents since the organic compounds are usually volatile and will be dissipated. **Asterion** - yes, you could use iodate or other iodine compounds (remember tincture of iodine as a local antiseptic). Off the top of my head I can’t tell their relative effectiveness compared to either bromine or chlorine. Most chemical additives for controlling bacteria, as **Qadgop the Mercotan** has stated, are now organic compounds containing either/or chlorine and bromine. Because chlorine is a gas it has a much stronger odor component than bromine which is a liquid at room temperature. ---
**Author:** ![Arwin](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@Arwin](https://boards.straightdope.com/u/Arwin)\ **Post date:** [October 25, 2005, 9:30am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/28 "2005-10-25T09:30:32Z")
> [@Waterman](#): > > If this is true then why does the USDA still recommend cooking pork to an internal temperature of 160-degrees F? Read carefully … how long do you cook your pork, hmmm? 😉 ---
**Author:** ![Waterman](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Waterman](https://boards.straightdope.com/u/Waterman)\ **Post date:** [October 25, 2005, 3:52pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/29 "2005-10-25T15:52:43Z")
> [@Arwin](#): > > Read carefully … how long do you cook your pork, hmmm? 😉 The point is that 140-degrees is not sufficient to kill pathogenic bacteria in water no matter how long the exposure is. There are some bacteria, as already pointed out I believe, that actually thrive at such temperatures. You have to reach much higher temperatures to eliminate bacteria from water if that is your only source of protection. ---
**Author:** ![Dishfunctional](https://avatars.discourse-cdn.com/v4/letter/d/35a633/32.png) [@Dishfunctional](https://boards.straightdope.com/u/Dishfunctional)\ **Post date:** [October 25, 2005, 10:19pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/30 "2005-10-25T22:19:24Z")
> [@Waterman](#): > > Bad reasoning here - evaporation only allows for water vapor to escape, the dissolved inorganic (sodium, sulfate, hardness, alkalinity, etc.) constituents in the water plus the inorganic additives that you use for treatment will just continue to concentrate until it finally start getting either or both soft or scale on your wetted surfaces. To maintain the concentration of dissolved constituents at a reasonable level it is recommended to drain off some of the water on a regular basis and then replace that with fresh water. One of the reasons (see below for another) that most chlorine and bromine compounds that are used for treatment are organic is because they will not add any dissolved constituents since the organic compounds are usually volatile and will be dissipated. Good point, **Waterman**. Maybe we’re fortunate in that we have a small tub, about 400 gallons, and we splash a lot. ---
**Author:** ![Dishfunctional](https://avatars.discourse-cdn.com/v4/letter/d/35a633/32.png) [@Dishfunctional](https://boards.straightdope.com/u/Dishfunctional)\ **Post date:** [October 25, 2005, 10:25pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/31 "2005-10-25T22:25:57Z")
> [@Waterman](#): > > The point is that 140-degrees is not sufficient to kill pathogenic bacteria in water no matter how long the exposure is. There are some bacteria, as already pointed out I believe, that actually thrive at such temperatures. You have to reach much higher temperatures to eliminate bacteria from water if that is your only source of protection. Actually, the **REAL** point is if your hot tub gets up to 140º, you goy WAY TOO MUCH WOOD under that there cider drum, Gomer… and you just might be a redneck. 😃 ---
**Author:** ![Waterman](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Waterman](https://boards.straightdope.com/u/Waterman)\ **Post date:** [October 25, 2005, 11:18pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/32 "2005-10-25T23:18:13Z")
> [@Dishfunctional](#): > > Actually, the **REAL** point is if your hot tub gets up to 140º, you goy WAY TOO MUCH WOOD under that there cider drum, Gomer… and you just might be a redneck. 😃 What’s beyond redneck? :rolleyes: Stop - Let’s not turn this into one of those conservative vs. liberal things - this is a science oriented thread. - OK ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [October 25, 2005, 11:25pm UTC](https://boards.straightdope.com/t/hot-tub-question/327560/33 "2005-10-25T23:25:39Z")
> [@Waterman](#): > > The point is that 140-degrees is not sufficient to kill pathogenic bacteria in water no matter how long the exposure is. There are some bacteria, as already pointed out I believe, that actually thrive at such temperatures. You have to reach much higher temperatures to eliminate bacteria from water if that is your only source of protection. Can you name one? That would be common in hot tub water? ---
**Author:** ![Dishfunctional](https://avatars.discourse-cdn.com/v4/letter/d/35a633/32.png) [@Dishfunctional](https://boards.straightdope.com/u/Dishfunctional)\ **Post date:** [October 26, 2005, 1:19am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/34 "2005-10-26T01:19:52Z")
> [@Waterman](#): > > Stop - Let’s not turn this into one of those conservative vs. liberal things - this is a science oriented thread. - OK You have my word. I came in here to get AWAY from that shit! That’s what hot tubs are for! ---
**Author:** ![Waterman](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Waterman](https://boards.straightdope.com/u/Waterman)\ **Post date:** [October 26, 2005, 1:44am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/35 "2005-10-26T01:44:48Z")
> [@Shalmanese](#): > > Can you name one? That would be common in hot tub water? I do not have a reference handy for the actual maximum temperature; however, the pasteurization process (while not practical as a means of treating municipal water) requires a temperature of 62.8 degrees C (145 degrees F) for 30 minutes. The waterborne bacteria that I can think of most readily are _giardia lamblia_ and _cryptosporidium_, which are both waterborne bacteria and have the been the cause of several major outbreaks over the last decade. The LT2 (Stage 2 Long Term Surface water rules) regulations will require, if my memory is correct (as I am home and not at work) somewhere between a 4- to 6-log removal for surface water supplies and ground water under the influence. I would certainly not feel the least bit safe relying on temeratures that we are discussing (around 140 degrees F) to provide the necessary kill rate to prevent a waterborne disease. There are other bacteria that also linked to waterborne illnesses that I would be happy to list if you want me to get out my microbiology book and dust it off. My point, supported by others, is that hot tubs are a great environment for the growth of most bacteria (pathogenic or not). ---
**Author:** ![Waterman](https://avatars.discourse-cdn.com/v4/letter/w/b2d939/32.png) [@Waterman](https://boards.straightdope.com/u/Waterman)\ **Post date:** [October 26, 2005, 1:46am UTC](https://boards.straightdope.com/t/hot-tub-question/327560/36 "2005-10-26T01:46:49Z")
> [@Dishfunctional](#): > > You have my word. I came in here to get AWAY from that shit! That’s what hot tubs are for! Amen to that!!! Go back to the hot tub and enjoy. [Previous page](https://boards.straightdope.com/t/hot-tub-question/327560.md?page=1)