# How long to let the water run before using for tea or coffee? **URL:** \ **Category:** Factual Questions\ **Created:** [April 15, 2008, 2:49am UTC](https://boards.straightdope.com/t/how-long-to-let-the-water-run-before-using-for-tea-or-coffee/445388 "2008-04-15T02:49:09Z")\ **Posts on this page:** 4\ **Page:** 2
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [November 28, 2011, 7:50pm UTC](https://boards.straightdope.com/t/how-long-to-let-the-water-run-before-using-for-tea-or-coffee/445388/21 "2011-11-28T19:50:47Z")
> [@constanze](#): > > The other reason that you let water run to get cold water and not warm water for all cooking activities is that warm water comes from the boiler, which means not only lots of bacteria (including salmonella which survive boiling just fine), but also often special chemicals (to keep the boiler from calcifying). So warm water from a boiler is good enough for washing outside, but not for putting inside your body. :rolleyes: Care to name any of those evil special chemicals, and explain what’s so dangerous about them? Also, salmonella does not survive boiling. [This USDA page](http://www.fsis.usda.gov/factsheets/salmonella_questions_&_answers/#9) cites 165 F as sufficient to kill salmonella in food. No food-borne pathogens survive boiling. Some of the _toxins_ produced by certain bacteria, such as endotoxins and enterotoxins, can survive high temperatures even above boiling. Maybe you could name pathogens that actually lurk in a commercial hot water system? ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [November 30, 2011, 3:34am UTC](https://boards.straightdope.com/t/how-long-to-let-the-water-run-before-using-for-tea-or-coffee/445388/22 "2011-11-30T03:34:46Z")
> [@constanze](#): > > The other reason that you let water run to get cold water and not warm water for all cooking activities is that warm water comes from the boiler, which means not only lots of bacteria (including salmonella which survive boiling just fine), but also often special chemicals (to keep the boiler from calcifying). So warm water from a boiler is good enough for washing outside, but not for putting inside your body. Nonsense! The OP is talking about water from the cold water tap, which might be warm because it has been sitting in uninsulated pipes in room-temp rooms all night, and so might have warmed up to near room temperature (70°F or so). That is NOT water that has been into a boiler at all. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [November 30, 2011, 3:40am UTC](https://boards.straightdope.com/t/how-long-to-let-the-water-run-before-using-for-tea-or-coffee/445388/23 "2011-11-30T03:40:47Z")
> [@Plan\_B](#): > > Do I have to let it run long enough to get rid of all the water that’s been sitting around inside the building all weekend, all 21 floors worth? How would the water that has been sitting around inside the water mains under the street all weekend be any better than “the water that’s been sitting around inside the building all weekend”? The only possible difference I could see is that water from the street water mains might be colder, since that sitting in the pipes inside the building might have warmed up to near room temperature. (Assuming no problems with poor plumbing, lead pipes, etc.) ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [November 30, 2011, 4:14am UTC](https://boards.straightdope.com/t/how-long-to-let-the-water-run-before-using-for-tea-or-coffee/445388/24 "2011-11-30T04:14:27Z")
**PlanB** , you may have heard some distant bells about legionella, a bacterium which grows in still waters - but it needs oxygenated water. It’s a problem if the house’s cold water system includes a big deposit, not a problem when water goes directly from the pipes outside to yours. Spanish legionellosis-prevention regs focus on piped water, but the information I find about it in English is more focused on A/C systems than on piped water. **constanze** , EDTA (that chemical used to prevent calcification) would only be dangerous to people with hemophilia (who should be getting treated for it in any case), and in much higher concentrations than you find it in water. [Previous page](https://boards.straightdope.com/t/how-long-to-let-the-water-run-before-using-for-tea-or-coffee/445388.md?page=1)