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April 22, 2009 7:23 AM   Subscribe

Is "old" water safe to drink?

I have no problem leaving a cup of water on my bedside table for a straight week and drinking out of it. I'll also drink out of a (previously opened) water bottle that's been rolling around on the floor of the car for days. SO doesn't even like to drink water left out over night, and has a half-dozen half-empty water bottles in his floorboards. I argue that water doesn't "go bad" or "spoil" under normal circumstances. SO claims this is "gross!"

Who's right?
posted by kidsleepy to Food & Drink (28 answers total) 2 users marked this as a favorite
Why does water taste stale after sitting out overnight?

Also, algae will grow in water exposed to sunlight, like those bottles left on the floor of a car.
posted by bunnytricks at 7:31 AM on April 22, 2009

Best answer: The potential issue is that when you drink out of it you contaminate it with oral flora and whatever organisms may be on your lips and so forth. If you leave it long enough you will almost certainly see some mold start to grow. On the other hand, water is not the best culture medium out there, and whatever organisms are in it after you drink out of it probably came from your own body, so it's not the same as drinking from a sippy cup of chocolate milk that sat in the car for a couple of days (my daughter is now very careful to put all left-over drinks in the fridge). There is a certain ick factor but the health risk, while not zero, is pretty small.
posted by TedW at 7:32 AM on April 22, 2009

Response by poster: So it tastes stale, but is it unsafe?
posted by kidsleepy at 7:33 AM on April 22, 2009

It's not just gross, it's dangerous. Dust, bacteria, and worse. Previously.
posted by devnull at 7:34 AM on April 22, 2009

So it tastes stale, but is it unsafe?

Why risk it? It's a glass of water. Just replace the damn thing :)
posted by devnull at 7:35 AM on April 22, 2009 [1 favorite]

Response by poster: devnull: I don't see anything in the previous thread that indicates it's dangerous? Am I missing something? I'm not refuting that there is bacteria in water (from backwash, etc), but there's bacteria in/on everything. Is there any evidence that "old" water will make you sick or harm you in any way? If so, how likely is it?

Let's assume "old" is one month, not years or anything crazy, and that the water is USA tap water or bottled water. Just your average set of circumstances.
posted by kidsleepy at 7:46 AM on April 22, 2009

If you live in an area (like the southeastern US) where there are bugs everywhere all the time, there might be little critters in your house that prefer to poop their eggs out in small patches of still water. You have to ask yourself, "am I ok with the possibility of eating mosquito babies?"
posted by phunniemee at 7:47 AM on April 22, 2009

Have you run into any problems so far?
posted by Pants! at 7:56 AM on April 22, 2009

Best answer: kidsleepy: I know you want to win the argument with your SO, but hold on a minute.

Cost benefit analysis time. Benefit of one week/month old water versus potential risk that something dangerous hasn't grown in it?

Micro-organism time. It's water, the worlds most popular solvent. The basis for life. Of course stuff will grow in it. See Legionellosis for one.

Have you run into any problems so far?
This isn't a proof or scientific study. Even if you haven't yet, this doesn't mean you won't.
posted by devnull at 7:59 AM on April 22, 2009 [3 favorites]

Response by poster: haha devnull, I TOTALLY want to win this argument!
posted by kidsleepy at 8:01 AM on April 22, 2009

I'm not refuting that there is bacteria in water (from backwash, etc), but there's bacteria in/on everything.

Which is why you cook meat, boil water (if it's untreated), wash your hands, etc. Your body is able to fight off most bacteria with no problems, but limiting the amount of potentially hazardous material that enters your system is usually a good idea. The water treatment plant or bottled water companies are regulated and need to follow certain guidelines about how much bad stuff can be in the water they sell you, but once you leave it lying around exposed to contaminates there's no telling what you're drinking.
posted by burnmp3s at 8:02 AM on April 22, 2009

However, chlorine treatment alone, as used in the routine disinfection of water, may not kill some enteric viruses and the parasitic organisms that cause giardiasis, amebiasis, and cryptosporidiosis.
from Risks from Food and Water (Drinking and Recreational)

Also see Drinking Water Treatment and Sanitation for Backcountry & Travel Use.
posted by devnull at 8:06 AM on April 22, 2009 [1 favorite]

Best answer: As someone with a fair amount of microbiology background, I can tell you that the water in your cup is certainly being contaminated with things like dead skin cells (dust), pollen, microfungi, and yes, lots of bacteria. Things like mosquito larvae mentioned above are more rare indoors, but not outside the realm of possibility.

That said, I don't have any problem drinking water that's been left out overnight. Your stomach acid is an incredibly hostile environment to most microorganisms, and your immune system has a pretty impressive array of defenses as well.

So overnight: sure. A day or two: fine. A week? Yeah, you'll probably okay, but why take a chance? devnull gets it right. In a cost-benefit analysis, the potential downsides are far greater than the effort it takes to walk to the faucet and get a new glass of water.
posted by chrisamiller at 8:14 AM on April 22, 2009

One other thing to consider, at least in the bottled water instance, is what can and will leach out of the plastic into the water when left for awhile in the heat (e.g. on the floor of your car).
posted by Pomo at 8:49 AM on April 22, 2009

There are still concerns that Bisphenol A leeches out of polycarbonate bottles much more quickly when exposed to heat. Bisphenol A is an estrogenic compound that may be unsafe for chidren and fetuses and may promote certain cancers. Polycarbonate bottles have a "7" on the bottom. Plastic industry testing concludes that there is no danger and there really isn't that much leeching anyway.
posted by pointilist at 9:06 AM on April 22, 2009

unsafe for children also.
posted by pointilist at 9:07 AM on April 22, 2009

Use "old" water to water the plants - that way it doesn't go down the drain. You stay healthy, your SO stops worrying about cross-contamination from holding your week-old-watery hands, your plants are happy. Win-win-win.
posted by mdonley at 9:10 AM on April 22, 2009

No. If anything it will boost your immune system.
posted by torquemaniac at 9:11 AM on April 22, 2009

If anything it will boost your immune system.

posted by scody at 9:14 AM on April 22, 2009

Unsafe for pets, too... Normally you'd give dogs or cats or any other pet fresh water every day, right?

With plastic water bottles, every time I forget one with some water in it somewhere for a few days, when I open it again it does smell so funny, I just throw it away. Especially if it's been sitting in the sun or somewhere warm.

Those being smaller bottles I drink straight from. Bigger bottles that I'd maybe use a glass for, they still smell fine if they're stored in the fridge or a cool place.

On top of what everyone else said - from another Food Safety link:

Researchers at the University of Calgary collected 75 water bottles from elementary students. ... Salvia and food particles can get into the water bottle and if left sitting on a desk at room temperature for several hours, bacteria can grow to harmful levels.
These commercial water bottles are made with plastic designed and intended for one-time use.

If I were you, I'd try to win a different argument about those half-dozen half-empty bottles left around on the floor...
posted by bitteschoen at 9:48 AM on April 22, 2009

My brother left a glass half full of water on his nightstand for a few weeks one time. Eventually, something grew in there. Don't think it was algae, at least it wasn't green, so maybe mold. It was grayish and floaty. Pretty gross.

Eventually something will start growing in the water (and things are already growing before you can visibly see them). If that doesn't bother you, have at it. Me, I'll drink a glass of water the next day, and reuse glasses themselves for a few days. But I wouldn't drink a glass left out a week.
posted by 6550 at 10:49 AM on April 22, 2009

A compromise: Get the bf a stainless steel permanent water bottle. It's incredibly wasteful to ship water around the country in plastic bottles, and your tap water is as safe or safer than bottled water. The US enjoys universal safe drinking water from the tap. If it's too chlorinated, use a filter. Rinse the steel bottle and refill.
posted by theora55 at 11:49 AM on April 22, 2009

The US enjoys universal safe drinking water from the tap.

Not always.
posted by dmd at 12:29 PM on April 22, 2009

My grandparents store lots of bottles of water around the house "for the war." I cleaned out a lot of the bottles a few years ago and in a lot of them, the water had turned very brownish. This was tap water stored in closets, under beds, etc. in old vodka bottles for god knows how long.
posted by artychoke at 1:15 PM on April 22, 2009

The easiest thing to do, IMO, is to put a cover on the water glass. Custom made covers are available, but you can just use anything that is heavy enough to stay put, but light enough not to make the glass top-heavy.

This doesn't solve all of the potential problems, but it should help.
posted by paisley henosis at 1:47 PM on April 22, 2009

theora55 A compromise: Get the bf a stainless steel permanent water bottle.

Or better yet, buy a Sigg. For the environment, or for your health.

All joking aside, Sigg really is good stuff. And I'm just a fan.
posted by paisley henosis at 1:52 PM on April 22, 2009

Use a different vessel for the water you keep around, and pour the water into a drinking glass. Wash the glasses. If you don't drink from the pitcher/bottle/whatever, it will stay fine for as long as it takes you to drink it, as long as you're drinking a few glasses each day.
posted by cgc373 at 1:03 AM on April 23, 2009

SO here.

I am all for the “listen, I’m just building my immune system” argument. I will eat 3 day old pizza and cold coffee like a geek in the middle of a [your comment here] marathon. However, my understanding is that wild animals rarely drink still water. As such, I have held this belief even when camping; I always gather running water to sterilize for drinking purposes. (Yes, I know there are exceptions in areas). Let me ask the reader, do you think a humans natural instinct (for those of you who still have them), without access to medical supplies, would still drink the funky water without sterilizing it first?

Theora55 and paisley henosis – As I appreciate your comments, I am not a fan of anything with “permanent” uses in metal, especially aluminum. (Previous). My personal vendetta's aside, I am still intrigued why the bottles you linked to look a lot like this.
posted by thetenthstory at 9:12 PM on April 30, 2009

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