I often suffer from dry mouth, so I keep a bottle of water in the car. It sits in there for about a week, until it’s empty. We recently had some very hot days, and when I picked it up for a drink, I noticed that the water had a greenish tint to it. Being very thirsty, I drank some anyway, about .75 of a cup. It didn’t make me sick, or at least I had no symptoms. So what was this greenish stuff that I drank?
Algae.
There are some kinds of algae that are toxic, but I have a (crazy) friend who never washes his water bottle, and is always drinking green water, and he’s not dead yet…
While you may or may not get ill as a result, why would you want to take a chance? I might wait a day or two before cleaning and refilling, but during the summer I would be more cautious. Bacteria can live in surprising inhospitable environments.
Drink it. Make you strong.
I can’t seem to find a cite for it now so it may be only an urban legend, but I was pretty sure I’ve read a news article or two that told the story of a person who died or became very very ill after drinking water that had been opened, left in the car and sealed again for a while. Certain bacteria had time to grow and it was really bad.
Discussion from snopes board about refilling plastic bottles:
http://msgboard.snopes.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=108;t=000581;p=1
Snopes page about plastic bottles with lots of different stuff about supposed dangers of plastic bottles:
No offense, but you must have been seriously, SERIOUSLY thirsty.
I can’t remember where I read it, but apparently you should never leave a bottle of water in the car and let it sit there like that all the time. Bring a fresh bottle with you whenever you go somewhere, and take it with you.
If you must refill a bottle, buy one of those sports bottles, and keep it washed and refill it whenever you go somewhere (bathroom, drinking fountain, etc). I don’t care how thirsty you are, is it really worth getting sick?
It’s a controversial opinion, but I’m going to go out on a limb and suggest that if something that isn’t supposed to be green turns green, you probably shouldn’t ingest it.
I have a half-gallon juice bottle at my work station, which I keep full of water, and consume the contents every day. I just refill it, and never rinse it out. If after a few months I notice some residual buildup around the mouth, I wipe it off with a rag. Same bottle for several years, no ill effects.
I always keep a couple of milk jugs full of water in my car, one in the trunk, one on the floor of the back seat. I have left them there for more than a year, and drinking from them after that time has neither affected their safe potability nor their flavor.
In countries prone to water shortages, cisterns full of water are mounted on the roof of every house, which are refilled when there is running water. During the dry season of 6-8 months, the cistern full of water is all the household has, and ir remains perfectly safe to drink. The cistern doesn’t get cleaned out for years, and it’s incredibly foul looking in there, but there are no pathogens.
:dubious:
panache, are you glowing in the dark yet?
My guess would also be algae wich may well be harmless, but damn. Drinking it?
I refill water bottles with tap water many times over, but green or discolored water would make my lizard brain go “wait, whaaaa? Umm, no.” It’s a hardwired response, the same as an aversion to snakes or maggots near food. Danger, danger.
Does it have to do with keeping water cooped up in a closed bottle without fresh air? Versus drinking pond water?
For several years I lived in a rural area – a trailer in a forest – drinking untreated water from a hole in the ground, occasionally skimming off the algae scum. So yeah, I glowed in the dark – but chiroptera asks about that like it’s a bad thing!? 
Here’s a thought. Wash and refill the bottle daily. Crazy, I know.
I’ve read about people, in a pinch, drinking their own urine. So there’s that.
Some people do that for fun though. Never heard of drinking days old green water for fun. So there’s that.
Heh. I was thinking more along the lines of dying from thirst. But I’ll give you that. So there’s that.
Our house has three water tanks which are filled from an inconsistent municipal supply, the tanks are black and sealed but there is a hella lot of moss and stuff growing in there. My wife won’t drink it unboiled, but I do. I’m not dead…yet.
Urine (from a healthy person) is essentially sterile with the only source of contamination being at the exit.
The “greenish tint” in the water was most certainly some kind of cyanobacteria (“blue-green algae”). For the most part, such algae are not toxic in normal quantities, but under some conditions certain strains (most notably Cylindrospermopsis) can release cytotoxins which can cause adverse affects in the gastrointestinal system and kidney and liver organs. Because drinking water has almost no sugars or anything that can break down into simple carbohydrates (basically, whatever it gets from the backwash) in it, the growth is self-limiting. The same is not true for fruit juice or anything with added sugars, though the high acid environment of carbonated beverages will inhibit bacterial growth as long as the beverage remains significantly carbonated.
In general cyanobacteria are not a significant ingestion hazard in the fashion that anaerobic bacteria or their toxic byproducts tend to be, and consuming “moldy” water is not a significant health hazard unless one has an immune reaction to allergenic products of the organism. On the other hand, it is easy enough to rinse out the bottle when refilling it, which even without thorough cleaning will limit the growth of any organisms residing within it. Again, a container containing liquid with any form of sugar in it, on the other hand, should be thoroughly washed and cleaned after use, and contents discarded if it remains standing unrefrigerated for more than a few hours.
Stranger
For the record, I’m still alive and well. My partner says I glow in the dark, and always have.
But do you glow green ?