# Unsealed Bottle of Water Safe for How Long? **URL:** \ **Category:** Factual Questions\ **Created:** [April 2, 2006, 4:07pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951 "2006-04-02T16:07:06Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![xiix](https://avatars.discourse-cdn.com/v4/letter/x/d6d6ee/32.png) [@xiix](https://boards.straightdope.com/u/xiix)\ **Post date:** [April 2, 2006, 4:07pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/1 "2006-04-02T16:07:06Z")
Google has failed me yet again. What is a good rule of thumb for drinking previously-opened bottles of water? I generally am most comfortable with 12 hrs at room temperature, but slowly develop hesitations after that point, though for all I know my evians are perfectly safe to drink for a week? What (if any) micro-organisms might be attracted to my bottle anyways? cheers. ---
**Author:** ![Excalibre](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Excalibre](https://boards.straightdope.com/u/Excalibre)\ **Post date:** [April 2, 2006, 8:28pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/2 "2006-04-02T20:28:08Z")
> [@xiix](#): > > Google has failed me yet again. What is a good rule of thumb for drinking previously-opened bottles of water? I generally am most comfortable with 12 hrs at room temperature, but slowly develop hesitations after that point, though for all I know my evians are perfectly safe to drink for a week? What (if any) micro-organisms might be attracted to my bottle anyways? > > cheers. You’re talking bottles of water that you purchase? Um, where do you purchase it and how do they store it? Because the stuff will be sitting on the shelf at the store for weeks at room temperature in most stores; I don’t think you need to worry about twelve hours. ---
**Author:** ![Harriet\_the\_Spry](https://avatars.discourse-cdn.com/v4/letter/h/e56c9b/32.png) [@Harriet\_the\_Spry](https://boards.straightdope.com/u/Harriet_the_Spry)\ **Post date:** [April 2, 2006, 8:31pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/3 "2006-04-02T20:31:31Z")
The bottles will be sitting on the shelf sealed for weeks. But the OP is asking about once they have been opened and perhaps partially used. Does anyone have an answer? ---
**Author:** ![Operation\_Ripper](https://avatars.discourse-cdn.com/v4/letter/o/34f0e0/32.png) [@Operation\_Ripper](https://boards.straightdope.com/u/Operation_Ripper)\ **Post date:** [April 2, 2006, 9:37pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/4 "2006-04-02T21:37:04Z")
For what it’s worth, [Here’s](http://www.realsimple.com/realsimple/content/print/0,22304,676079,00.html) a list of shelf life for just about everything else, except water remarkably. ☹ ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [April 2, 2006, 9:42pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/5 "2006-04-02T21:42:42Z")
The nice thing about water is that it doesn’t rot. ---
**Author:** ![Speaker\_for\_the\_Dead](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@Speaker\_for\_the\_Dead](https://boards.straightdope.com/u/Speaker_for_the_Dead)\ **Post date:** [April 2, 2006, 9:53pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/6 "2006-04-02T21:53:51Z")
I’ve drunk glasses of water that have sat on the night table in my dusty room for days on end, and I haven’t gotten sick. In fact, that that might happen never occurred to me. ---
**Author:** ![GrandWino](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grandwino/32/67_2.png) [@GrandWino](https://boards.straightdope.com/u/GrandWino)\ **Post date:** [April 2, 2006, 9:55pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/7 "2006-04-02T21:55:42Z")
I was actually just wondering this same thing yesterday. I suppose if you sealed the bottle w/ the cap after you drank, any micro organisms would have trouble growing due to lack of oxygen, though there might be enough left in the bottle to let them grow like crazy. ---
**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:** [April 2, 2006, 10:00pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/8 "2006-04-02T22:00:00Z")
> [@HelloNinja](#): > > I was actually just wondering this same thing yesterday. I suppose if you sealed the bottle w/ the cap after you drank, any micro organisms would have trouble growing due to lack of oxygen, though there might be enough left in the bottle to let them grow like crazy. without something to feed on, micro-organisms are going to have a lot of trouble reproducing just on a bit of air and water. ---
**Author:** ![xiix](https://avatars.discourse-cdn.com/v4/letter/x/d6d6ee/32.png) [@xiix](https://boards.straightdope.com/u/xiix)\ **Post date:** [April 2, 2006, 11:48pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/9 "2006-04-02T23:48:16Z")
I suppose being sheltered would protect the environment from the usual problematic critters big and small that ruin exposed stagnent water outside. So are we working towards a theory that its good indefinately? Assuming no wacky molecular decomposition of the material comprising the bottle itself. I can safely drink a bottle of water thats was opened a month prior? Also would need to assume that the humidity in whereever i’m storing it is just right to minimize evaporation. I’m pretty sure the water would develop an increasingly unpleasant taste, if microorganisms ain’t causing that, then what could be? ---
**Author:** ![ParentalAdvisory](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@ParentalAdvisory](https://boards.straightdope.com/u/ParentalAdvisory)\ **Post date:** [April 3, 2006, 1:37am UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/10 "2006-04-03T01:37:52Z")
> [@Speaker for the Dead](#): > > I’ve drunk glasses of water that have sat on the night table in my dusty room for days on end, and I haven’t gotten sick. In fact, that that might happen never occurred to me. One thing I’ve noticed when I’ve left water out for a day in a glass, is that there will be a small film of something nasty on top of it. Likely just dust particles collecting on top of it for the day. After seeing that, I won’t drink it anymore. Never got sick from it before when I did drink it, but after seeing that, I don’t want to take the chance either. But a bottle of water probably wouldn’t have this issue if closed up. In which I will drink from for maybe 4 days afterwards, never a problem with getting sick from that either. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [April 3, 2006, 1:50am UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/11 "2006-04-03T01:50:28Z")
I think there is an erroneous assumption that bottled water is pure before it is opened. There are[no specific FDA standards prohibiting the presence of harmful bacteria in bottled water](http://www.nrdc.org/water/drinking/bw/chap1.asp): > [@](#): > > An estimated 60 to 70 percent of the bottled water sold in the United States, according to FDA interpretations, is exempted from FDA’s contamination limits and specific bottled water standards because it is bottled and sold in the same state. > [@](#): > > FDA’s rules also exempt many forms of what most of us would consider “bottled water” from all of its specific water-testing and contamination standards. If the product is declared on the ingredient label simply as “water,” “carbonated water,” “disinfected water,” “filtered water,” “seltzer water,” “sparkling water,” or “soda water,” it is not considered “bottled water” by FDA, [13] nor, as noted in Chapter 4, do most states regulate this water as bottled water. For these products, the specific FDA contamination standards and water quality testing requirements for bottled water are not applicable. No contamination monitoring is required, and only a vague narrative legal standard applies, stating that the water cannot be “adulterated” – a term not specifically defined and, to date, apparently never enforced against any of these products by FDA. \*\*Therefore, the generalized FDA “good manufacturing practice” requirements applicable to these waters[14] set no specific contamination standards. \*\* The same is true with most state regulations. > > Even what FDA defines to be “bottled water” is exempt from many of the standards and testing requirements that apply to tap water. This appears to directly contradict the letter and the spirit of the Federal Food, Drug, and Cosmetic Act (FFDCA), which requires – under a provision strengthened in 1996 – that FDA’s bottled water standards must be at least as stringent as tap water standards. [15] For example, EPA’s rules clearly prohibit tap water from containing any confirmed E. coli or fecal coliform bacteria (bacteria that are indicators of possible fecal matter contamination often associated with waterborne disease). [16]\*\* FDA has no such prohibition for bottled water; instead, any type of coliform bacteria is allowed up to a certain level. \*\* [17] (See Table 1 for a comparison of EPA and FDA rules.) > > Similarly, a big city has to test its tap water 100 times or more each month for coliform bacteria – many times a day, on average – yet bottled water (even at an enormous bottling plant) must be tested for coliform bacteria only once a week under FDA rules. Moreover, while high overall levels of bacteria (known as heterotrophic-plate-count [HPC] bacteria) can be counted toward bacteria violations for city tap water (in the absence of adequate disinfection), as described in Chapter 4, **FDA bowed to bottled water industry arguments and decided to apply no standards for HPC bacteria in bottled water. HPC bacteria are commonly found in bottled water**. So your bottled water that has been sitting around opened for a few days is probably no more of a threat than it was when it was sealed. ---
**Author:** ![sunacres](https://avatars.discourse-cdn.com/v4/letter/s/4491bb/32.png) [@sunacres](https://boards.straightdope.com/u/sunacres)\ **Post date:** [April 3, 2006, 4:16pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/12 "2006-04-03T16:16:25Z")
> [@ParentalAdvisory](#): > > One thing I’ve noticed when I’ve left water out for a day in a glass, is that there will be a small film of something nasty on top of it. Likely just dust particles collecting on top of it for the day. After seeing that, I won’t drink it anymore. Never got sick from it before when I did drink it, but after seeing that, I don’t want to take the chance either. This “ick factor” came up in a recent thread about food in bathrooms. We’re pretty goofy, aren’t we? We’re so good at ignoring what we’re breathing, but hyper-sensitive about other modes of ingestion. Think about those dust motes that show up in bright sunshine! Yummy. ---
**Author:** ![ParentalAdvisory](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@ParentalAdvisory](https://boards.straightdope.com/u/ParentalAdvisory)\ **Post date:** [April 3, 2006, 7:57pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/13 "2006-04-03T19:57:45Z")
You’re right about that. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [April 3, 2006, 9:36pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/14 "2006-04-03T21:36:29Z")
As a habitual water-leaver-arounder, I can vouch for the apparent safety of abandonded water for days (in glasses) or weeks (in caped bottles). Eventually, it does start to taste like ass, however. And sometimes there’s little floaty things at the bottom, at which point I get icked out and open a new bottle of water. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [April 3, 2006, 9:37pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/15 "2006-04-03T21:37:35Z")
um…\*\*capped \*\*bottles. I don’t make costumes for my water bottles. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 4, 2006, 12:29am UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/16 "2006-04-04T00:29:23Z")
Water doesn’t go bad. It evaporates. There’s nothing for microbes to eat in water, or, if there is, it’s already so dirty that you have bigger problems to worry about. If there are bacteria and/or their byproducts in your water, they were there when it was bottled. Leaving it out does nothing. It’s harmless. Don’t panic. Relax. Life’s not out to get you. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [April 4, 2006, 1:26am UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/17 "2006-04-04T01:26:04Z")
I leave bottles of water near my bed so I don’t have to get up if I wake up thirsty (usually as an early symptom of an impending hangover). Sometimes I’ll drink a bottle quickly, but other times, I’ll leave it capped and by the bedside for weeks. I’ve never noticed any ill effects, although the water does start to taste vaguely “off” after a few weeks. ---
**Author:** ![Stan\_Shmenge](https://avatars.discourse-cdn.com/v4/letter/s/94ad74/32.png) [@Stan\_Shmenge](https://boards.straightdope.com/u/Stan_Shmenge)\ **Post date:** [April 4, 2006, 4:49am UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/18 "2006-04-04T04:49:49Z")
Once you drink out of the bottle, mouth bacteria are transferred to the water that can then provide a growth medium. I used to drink out of old sealed up water bottles until one day I took a big swig of some water where this process had really got started. I cannot describe the evil taste. I am now careful to finish my water one bottle at a time. A few days, fine. Longer than that and out it goes. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 4, 2006, 6:01am UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/19 "2006-04-04T06:01:24Z")
> [@Happy Wanderer](#): > > Once you drink out of the bottle, mouth bacteria are transferred to the water that can then provide a growth medium. I used to drink out of old sealed up water bottles until one day I took a big swig of some water where this process had really got started. I cannot describe the evil taste. I am now careful to finish my water one bottle at a time. A few days, fine. Longer than that and out it goes. Water is NOT sufficient to support bacterial growth alone. It’s possible there may have been some junk around the mouth of the bottle, but bacteria need nutrients other than water. ---
**Author:** ![Hombre](https://avatars.discourse-cdn.com/v4/letter/h/ecb155/32.png) [@Hombre](https://boards.straightdope.com/u/Hombre)\ **Post date:** [April 4, 2006, 3:17pm UTC](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951/20 "2006-04-04T15:17:38Z")
I recently drank from a opened then sealed water bottle that had been in my car for months. No problems. > [@xiix](#): > > I’m pretty sure the water would develop an increasingly unpleasant taste, if microorganisms ain’t causing that, then what could be? I don’t know but as a hiker I can tell you that boiled water also tastes bad and there are microorganisms in it. [Next page](https://boards.straightdope.com/t/unsealed-bottle-of-water-safe-for-how-long/350951.md?page=2)