The oxygen thing has to be rubbish – water at 100C has already boiled off all the oxygen (http://www.engineeringtoolbox.com/air-solubility-water-d_639.html ). So the oxygen has gone by the point the water reaches 100C the first time you boil it.

If you want to test it properly, you should do a number of samplings of it, see how she guesses and then use Fisher’s Exact Test to detect the statistical likelihood of her being better than chance at guessing which is which. It was developed specifically for such small sample size beverage related statistical challenges (to test if someone could tell the difference between milk in first vs tea in first)
http://en.wikipedia.org/wiki/Fisher’s_exact_test

Having said that, the obvious solution is to stop being an idiot and boiling tons of water just for a single mug. Then you remove that argument, because there isn’t any spare water. Kettles have numbers on the side that show you how much they have in, it just takes a minute to pour in cups and see which numbers correspond to a single mug, two mugs, or however many mugs you’re making, then forever after, you can just fill up to the right number. Or if you’re just making one mug, just fill up a mug with water and bung it in the kettle.

Isn’t there some chemical reaction to do with the hard water minerals once you boil and then cool water? I remember hearing that it’s when boiled water cools that the soluble minerals become insoluble, that’s why you should run cold water through your shower head after a shower to prevent it scaling up…… maybe..

As a student, I used to put teabags directly in the kettle- saving me precious stirring time. Until the kettle broke.

As for your original question- have the Mrs sectioned.

RE OP
Yes, Your wife is correct!
Never boil water more than once when making any hot drink!

Drain kettle, run cold tap for a few seconds, No stale pipe water please!
Boil water, leave for 30 seconds, add to cafetiere/mug.

Something to do with oxygen levels, I can always tell.

run cold tap for a few seconds, No stale pipe water please!

Unless your on a private supply, that pipe is miles long.
Even on the private supply at work there is still 250m pipe between the tap and the header tank.

Unless your on a private supply, that pipe is miles long.
Even on the private supply at work there is still 250m pipe between the tap and the header tank.

The further the pipe goes back, I’d assume the more often the pipe gets used, water gets used on many taps, washing machines, toilets?

I may be barking up the wrong tree?

she’ll have changed her mind by this time tomorrow.

The instruction on box of tea bags I bought recently said do not re boil water. A bit of googling suggests its to do with reduced oxygen in the water.

I’ve always been properly unconvinced by this argument. True, the hotter water is, the less soluble oxygen (and carbon dioxide, and other gasses) are in it.

But this is a fixed amount, if you’re bringing it to 100oC again, gasses aren’t less soluble the second time around.

Maybe if you have hard water, and you use water that’s been repeatedly boiled, you get concentrated minerals?

Similarly unconvinced by this, at least in an electric kettle with an auto-cut-off.
For the amount of water that’s lost as steam, I can’t imagine that there’d be any discernable increase in concentration.

I could possibly believe that if your kettle is dirty, then re-boiling, or leaving water to sit in it for a long time would affect the taste noticably.

Get your wife to google “how instant coffee is made“. After that she shouldn’t be quite so worried about whether you reboiled the water or not 😉

Thanks for all the replies guys. I’ll agree with the ones that think she’s a crazy bint. And on a similar note…WTF does it matter if the water or milk go in first? And don’t give me that burnt coffee bobbins!!

That tends to be an argument that tea drinkers make – and that it scalds the milk.
Which is fine. If you’re making tea in a tea pot.

If she’s drinking instant coffee-flavoured-drink, though, absolutely hot water in first, or it doesn’t dissolve properly.