# Does it make a difference how hot the water is for dishwashing? **URL:** \ **Category:** Factual Questions\ **Created:** [July 7, 2017, 10:49pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727 "2017-07-07T22:49:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Biggirl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biggirl/32/3294_2.png) [@Biggirl](https://boards.straightdope.com/u/Biggirl)\ **Post date:** [July 7, 2017, 10:49pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/1 "2017-07-07T22:49:27Z")
I know that boiling hot water is best to kill bacteria but you can’t put your hands in boiling hot water. Recently our dishwasher broke and I’ve had to wash dishes by hand. It has been a while and boy do I miss my dishwasher. But enough of my first world problems and on to my question. I’ve always washed dishes in water as hot as I can stand it, which is pretty hot. Sometimes it’s so hot, I can’t stand it but I figure what’s a bit of discomfort when it comes to eating with clean utensils. But am I really getting the dishes cleaner using just-short-of-scalding water as opposed to nice, comfortably not-so-friggin-hot water? What’s the water temp to clean ratio for dishes? ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [July 7, 2017, 10:52pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/2 "2017-07-07T22:52:57Z")
Hot water breaks down grease. I make my dishwater as hot as possible. I wear rubber gloves to protect my hands. Gloves are cheap. There’s no need to burn your hands. 😃 ---
**Author:** ![Biggirl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biggirl/32/3294_2.png) [@Biggirl](https://boards.straightdope.com/u/Biggirl)\ **Post date:** [July 7, 2017, 11:18pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/3 "2017-07-07T23:18:29Z")
[Found this handy-dandy chart](http://www.accuratebuilding.com/images/services/charts/hot_water_burn_scalding_lrg.gif) of water temps and scalding over time. But perhaps those temps are a bit too high for hand dish-washing. I’m wondering what is the bacteria cleansing difference between washing dishes at, say, 110 degrees (presumably comfortable) and 125 degrees (very hot to the touch)? ---
**Author:** ![Troy\_McClure](https://avatars.discourse-cdn.com/v4/letter/t/51bf81/32.png) [@Troy\_McClure](https://boards.straightdope.com/u/Troy_McClure)\ **Post date:** [July 7, 2017, 11:21pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/4 "2017-07-07T23:21:50Z")
Well, if cold water works fine for hands, shouldn’t it also work fine for dishes? [http://news.rutgers.edu/research-news/handwashing-cool-water-effective-hot-removing-germs/20170529](http://news.rutgers.edu/research-news/handwashing-cool-water-effective-hot-removing-germs/20170529) (At least for removing bacteria. As mentioned, hot water obviously helps dissolve grease and stuff). ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [July 7, 2017, 11:22pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/5 "2017-07-07T23:22:50Z")
Dishwasher manufacturers used to state that 135 F was the temperature that your hot water tank should be set to for best results. Maybe they still do, but I know a lot of dishwashers have built-in water heating coils now. ---
**Author:** ![Biggirl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biggirl/32/3294_2.png) [@Biggirl](https://boards.straightdope.com/u/Biggirl)\ **Post date:** [July 7, 2017, 11:56pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/6 "2017-07-07T23:56:37Z")
> [@Troy\_McClure](#): > > Well, if cold water works fine for hands, shouldn’t it also work fine for dishes? > > [http://news.rutgers.edu/research-news/handwashing-cool-water-effective-hot-removing-germs/20170529](http://news.rutgers.edu/research-news/handwashing-cool-water-effective-hot-removing-germs/20170529) > > (At least for removing bacteria. As mentioned, hot water obviously helps dissolve grease and stuff). Ah, thanks! FTR, you can melt grease just as easily with water hot enough to be hot but not one degree away from scalding. Hot to the touch is hot enough. ---
**Author:** ![Biggirl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biggirl/32/3294_2.png) [@Biggirl](https://boards.straightdope.com/u/Biggirl)\ **Post date:** [July 7, 2017, 11:58pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/7 "2017-07-07T23:58:50Z")
> [@Leaffan](#): > > Dishwasher manufacturers used to state that 135 F was the temperature that your hot water tank should be set to for best results. Maybe they still do, but I know a lot of dishwashers have built-in water heating coils now. As per the chart, 135 is very, very close to scalding after 5 seconds, which makes me think it’ll scald at a minute. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [July 8, 2017, 12:42am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/8 "2017-07-08T00:42:04Z")
Nearly all of your detergents also state antibacterial. I like the water hot enough that it is just slightly uncomfortable when my hands first enter. It cools rapidly but I don’t worry about it. A clean dish leaves nothing for bacteria to feed on. ---
**Author:** ![Channing\_Idaho\_Banks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/channing_idaho_banks/32/250_2.png) [@Channing\_Idaho\_Banks](https://boards.straightdope.com/u/Channing_Idaho_Banks)\ **Post date:** [July 8, 2017, 1:03am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/9 "2017-07-08T01:03:07Z")
If they’re squeaky clean it’s probably OK. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [July 8, 2017, 3:37am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/10 "2017-07-08T03:37:22Z")
I’ve never owned a dishwasher … meh … I do my dishes in hot but comfortable water … a few degrees in this range won’t make any difference with grease or germs … I’m not clear on this anti-bacterial thing … it doesn’t matter if we kill all the bacteria, if we leave food on the plates, bacteria will grow … ---
**Author:** ![Biggirl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biggirl/32/3294_2.png) [@Biggirl](https://boards.straightdope.com/u/Biggirl)\ **Post date:** [July 8, 2017, 3:47am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/11 "2017-07-08T03:47:39Z")
> [@watchwolf49](#): > > I’ve never owned a dishwasher … meh … I do my dishes in hot but comfortable water … a few degrees in this range won’t make any difference with grease or germs … > > I’m not clear on this anti-bacterial thing … it doesn’t matter if we kill all the bacteria, if we leave food on the plates, bacteria will grow … I’m not clear on what it is you’re not clear about. Who leaves food on dishes they’ve washed? Bacteria, however, are not so easy to spot. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [July 8, 2017, 3:56am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/12 "2017-07-08T03:56:46Z")
> [@Biggirl](#): > > I’m not clear on what it is you’re not clear about. Who leaves food on dishes they’ve washed? Bacteria, however, are not so easy to spot. Where there’s no food, there is no bacteria … at least not human pathogens … if all food was water soluble, we wouldn’t need soap … it’s the oil soluble food that temperature and soup clean away, with the bacteria in that part … ---
**Author:** ![Biggirl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/biggirl/32/3294_2.png) [@Biggirl](https://boards.straightdope.com/u/Biggirl)\ **Post date:** [July 8, 2017, 4:33am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/13 "2017-07-08T04:33:47Z")
> [@watchwolf49](#): > > Where there’s no food, there is no bacteria … at least not human pathogens … if all food was water soluble, we wouldn’t need soap … it’s the oil soluble food that temperature and soup clean away, with the bacteria in that part … So, if you can’t _see_ food, then all is well? Because that’s not true at all. I’m still not getting the point. Sorry, it’s me not understanding, I’m sure. ---
**Author:** ![Monty](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/monty/32/47_2.png) [@Monty](https://boards.straightdope.com/u/Monty)\ **Post date:** [July 8, 2017, 10:56am UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/14 "2017-07-08T10:56:19Z")
> [@watchwolf49](#): > > Where there’s no food, there is no bacteria … at least not human pathogens … if all food was water soluble, we wouldn’t need soap … it’s the oil soluble food that temperature and soup clean away, with the bacteria in that part … You wash your dishes with soup? [d&r] ---
**Author:** ![Evan\_Drake](https://avatars.discourse-cdn.com/v4/letter/e/b487fb/32.png) [@Evan\_Drake](https://boards.straightdope.com/u/Evan_Drake)\ **Post date:** [July 8, 2017, 12:37pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/15 "2017-07-08T12:37:47Z")
I remember when young that older stingy people used to wash dishes in cold water. Partly for environmental reasons sometimes, but mainly not to spend money. This was in Britain, wouldn’t apply in America. Plus they’d gone through wars and such. They seemed very old to me at age about 8, so I guess they didn’t die young from this odd practice. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [July 8, 2017, 2:54pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/16 "2017-07-08T14:54:49Z")
> [@Biggirl](#): > > So, if you can’t _see_ food, then all is well? Because that’s not true at all. I’m still not getting the point. Sorry, it’s me not understanding, I’m sure. I didn’t say anything about seeing food, in fact I go more by touch … run your hand across a plate and you can tell where the food particles are still stuck … I kinda wanted to avoid saying this … but every surface both inside and out has a layer of microbes … bacteria, protists, fungi … so it doesn’t matter how sanitary the plate is in the drying rack … it’s collecting microbes … these are harmless to humans, or humans would have died out long ago … What we’re doing is removing food-borne pathogens by removing the food … especially those microbes that cause dysentery … no way can we remove all the agents that cause this, but we can limit the ingestion to very small amount, small enough our own body’s defense mechanisms can handle and destroy the infection … a glomp of old food tends to form large colonies of these agents and once ingested overwhelm our body’s defenses … Anti-bacterial products kill 99.9% of bacteria, but it’s the other 0.1% that’ll kill ya … ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [July 8, 2017, 2:58pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/17 "2017-07-08T14:58:48Z")
If you’re so worried about food & bacteria sticking to plates, use paper ones and throw them away. After use, of course, but if you’re really paranoid, before. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [July 8, 2017, 3:16pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/18 "2017-07-08T15:16:43Z")
> [@Biggirl](#): > > Ah, thanks! FTR, you can melt grease just as easily with water hot enough to be hot but not one degree away from scalding. Hot to the touch is hot enough. This is correct. Although the hotter the water the less time is needed for all of the grease to soften. I don’t know if there’s any further beneficial effect to heating water above about 120F. The drying cycle should be hot enough to kill bacteria, and probably do a better job of it by removing water altogether. ---
**Author:** ![sbunny8](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@sbunny8](https://boards.straightdope.com/u/sbunny8)\ **Post date:** [July 8, 2017, 6:48pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/19 "2017-07-08T18:48:44Z")
> [@HoneyBadgerDC](#): > > A clean dish leaves nothing for bacteria to feed on. This. Cold/tepid/warm/hot/scalding/boiling water doesn’t matter in the slightest, as long as you get rid of the food. When there’s no food, the bacteria starve. The only reason for using hot water is to help loosen the food, so you don’t need as much scrubbing. ---
**Author:** ![Contemplation](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Contemplation](https://boards.straightdope.com/u/Contemplation)\ **Post date:** [July 8, 2017, 10:20pm UTC](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727/20 "2017-07-08T22:20:10Z")
Hotwater melts solid fats that are stuck to a plate or dish. Once the fat is melted, it can be rinsed or wiped off much easier. Have you ever had hard cheese stuck to a plate? That’s because the hardened fat need to be melted before it can be dissolved even with detergent. At higher temperatures, water can hold more solute. This means that hotwater will dissolve things more easily and this will make cleaning easier. [Next page](https://boards.straightdope.com/t/does-it-make-a-difference-how-hot-the-water-is-for-dishwashing/790727.md?page=2)