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Tap water that has been left to sit out slowly begins to acquire an off taste. Many assume that this is because of micro-organisms. Treated water's added chlorine will take care of small communities of these little guys, but at room temperature they begin to multiply rapidly and can really get the party started. Even with clean water and a clean glass; one sip introduces a host of germs to the mix, in addition to whatever the water may have picked up by ambient dust.
But that's not what makes old water taste stale. For that we can thank carbon dioxide. After about 12 hours tap water starts to go flat as carbon dioxide in the air starts to mix with the water in the glass, lowering its pH and giving it an off taste. But it's most-likely safe to drink.
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As for plastic water bottles that have been left out in the sun or the car, step away from the bottle, warns Dr. Kellogg Schwab, director of the Johns Hopkins University Water Institute. "A chemical called bisphenol-A, or BPA, along with other things used to manufacture plastic can leach into your water if the bottle heats up or sits in the sun," he explains. BPA, as you likely know, is a hormone disruptor has tentatively been linked to everything from heart disease to cancer. Schwab also says that plastic used for bottled water isn't meant to be washed or refilled, so use only one time and recycle. Or way better, don't buy them at all; use a refillable water bottle instead.
I like to let mine sit out until it acquires malarial mosquito larvae.
(Score: 5, Insightful) by TrumpetPower! on Friday July 24 2015, @01:01AM
I am unaware of anything other than old wives's tales to support that claim -- no empirical evidence, no physiological nor chemical mechanism, nothing. This is especially the case since rainwater, save for rare cases of modern contamination, is distilled water -- and the old wives typically have a quite favorable opinion of rainwater. Basically, the claim is equivalent to those made by homeopaths.
Besides which, a single serving of pretty much anything is going to have more minerals in it than you're going to get out of even many, many gallons of tap water. If you're relying on your water for your source of minerals, ur doin it rong.
If you can offer up some solid evidence or theory, I'd be happy to consider it, of course.
b&
All but God can prove this sentence true.
(Score: 5, Interesting) by N3Roaster on Friday July 24 2015, @02:05AM
In the case of coffee there's quite a bit of research on water quality and brewed coffee quality which goes back several decades but is also ongoing with the current UK barista champion and his chemist putting out a new book on the topic soon. I'm fortunate enough to live in a place where the city tap water is almost ideal for coffee brewing so distilled water produces a noticeably inferior brew, but the water spec at http://scaa.org/?page=resources&d=water-standards [scaa.org] does have good science behind it. Of course, most places are not so fortunate so I can easily believe that you're getting better tasting results compared with tap, but it's probably not as good as what you'd get from a good set of filters appropriate to your location and it's not as good as you'd get from water that's been engineered to spec. As an aside, using straight RO water without reintroducing some mineral content quickly destroys brewing equipment. Not an issue if you're doing a Chemex, but it's terrible for espresso machines.
Typica - Free software for coffee roasting professionals. [typica.us]
(Score: 2) by TrumpetPower! on Friday July 24 2015, @02:55AM
Thanks for that -- I had no clue.
It almost looks like one could add measured trace amounts of sodium and calcium chloride to make distilled water meet that spec. Is that correct? Might you have any further resources or information -- ideally, even, a recipe?
I'm using a French Press, but through experimentation I've come to a non-standard mode of operation. I sift grinds from a Lido 3, which probably isn't unusual. Immediately after adding the water, I very slowly plunge just enough so the bloom is immersed an inch or so. After several minutes of brewing, a very slow lifting of the plunger is enough to cause the grounds to rapidly settle, and I then immediately decant into a thermos. Other methods seem to cause excessive agitation which doesn't seem to do the coffee any good, and typically result in excessively high acidity in the brew.
The pot goes in the dishwasher every night, so I'm sure the mineral content of the water is irrelevant to its long-term function.
b&
All but God can prove this sentence true.
(Score: 2) by N3Roaster on Friday July 24 2015, @03:54AM
You don't have anything to worry about with the press so long as it's one that you can get spare parts for. The filter will eventually fray or you'll break the glass but that's nothing to do with the water. A few brands are part compatible with each other but if you've got something that you can't get parts for it was probably cheap enough that you won't care too much when it breaks. The method is a bit non-standard but I don't see anything wrong with it and if you like how the coffee tastes, that's what's important.
Unfortunately I haven't done a lot of work with water myself (minimal filtering gets me to spec and when I'm teaching there's usually an event sponsor taking care of the water) and I'm not sure where I left most of the literature I have to provide some good citations. It's not where it should be on my shelves so it's probably either back at work or lent to an employee, but stripping down the water and adding back into it is exactly how the water I use at events is produced, though at much larger scale than you'd do at home.
Typica - Free software for coffee roasting professionals. [typica.us]
(Score: 2) by TrumpetPower! on Friday July 24 2015, @02:58PM
If you do come across it, perhaps you could submit it as a story? Seems to me "Engineer your water for optimum taste" would be be far more deserving of attention than speculation about the safety of day-old water.
b&
All but God can prove this sentence true.
(Score: 2) by N3Roaster on Friday July 24 2015, @03:13PM
The next time I run across something new on the topic (should be soon) I'll keep that in mind. No sense submitting research from the 50s as news, I think.
Typica - Free software for coffee roasting professionals. [typica.us]