Boiling water

[fernynerdy]

Is it un-advisable to re-boil water that has already been boiled?

[smurfchops]

I shouldn't think so, but best to tip it out and use fresh. Don't overfill the kettle in the first place, think of the ozone and energy and all that !!

[natalie_1982]

Apparently you shouldn't reboil boiled water because it is already deoxygenated? Not sure if that is even a word, but I think that's right.

[woofgang]

I don't think that thre's a health risk but it makes lousy tea and real coffee if you use re boiled water....okay for gravy and pot noodle though!

[Donquixote]

natalie_1982's right... there's no problem health-wise with using re-boiled water, but tea and coffee taste better when the water's freshly boiled. Each time you boil the water, it loses more and more of it's oxygen which is, apparently, what is responsible for the loss of taste!

[Gef]

Boiling water has no oxygen dissolved in it. As it cools down oxygen, from the air, dissolves in it. So really it makes no difference. That's my opinion but shoot me down in flames if you think I am wrong.

[nickmo]

No reason not to re-boil dihydrogen monoxide, but don't use it for anything that needs to have flavour as as stated, the dissolved oxygen has been removed so affecting the properties of the stuff.

1. If a quantity of pure water be boiled rapidly for a short time in a vessel with a narrow aperture, or if it be subjected to the air-pump, the air exhausted from the receiver containing the water, and then be briskly agitated for some time, very nearly the whole of any gas the water may contain, will be extricated from it.

2. If a quantity of water thus freed from air be agitated in any kind of gas, not chemically uniting with water, it will absorb its bulk of the gas, or otherwise a part of it equal to some one of the following fractions, namely, 1/8, 1/27, 1/64, 1/125, &c. these being the cubes of the reciprocals of the natural numbers 1, 2, 3, &c. or 1/1, 1/23, 1/33, 1/43, &c. the same gas always being absorbed in the same proportion, as exhibited in the following table:-- It must be understood that the quantity of gas is to be measured at the pressure and temperature with which the impregnation is effected.

Courtesy of John Dalton (1766-1844)
'On the Absorption of Gases by Water and Other Liquids' Bored tonight? Read it here : http://web.lemoyne.edu/~giunta/dalton52.html whihc means that water standing will absorb gases from the atmosphere if they have been mechanically removed.

In a nutshell, refill with fresh.

[fernynerdy]

Thank you for all your answers. It's just that my company got an electric kettle recently to replace an old boiler and because we don't all make our drinks at the same time and so as not to waste water that has been boiled, we started wondering if it's ok to boil the remaining water again in the kettle.