Is Reboiling Water Bad?

One of my sisters used to come to my humble abode every Sunday morning to go for a swim and as usual after an hour swim, we were hungry and ready for a hearty breakfast of toasts and coffee. Then, I noticed my sister always pouring away whatever water I have left in my electric kettle and refilling it afresh.

When I could not retain my curiosity any longer, I asked her why she did that. She looked me in my eyes and asked "Why? Don't you know, you should because you are so widely read?" Then she continued to chirp "Its bad to reboil boiled water". When I asked "Why?", her reply was just "It's bad la". I was always skeptical about statement without any logical explanation, so I left it at that and humoured her whenever she was around.

Then this email found its way into my mail box recently with this newspaper report in a Chinese daily. Hah, now that I do have something in black & white, its time to investigate.

I found no evidence of any detrimental issue on reboiling water except this article written in another personal blog on the 10 tips for a better cup of tea; also someone intrigued by this issue which states that:

"The more oxygen that is dissolved in water, the better it tastes. So, to make sure you use water with the maximum amount of oxygen, don't re-boil any leftover water in your kettle. Water that is boiled too much becomes poorly aerated because oxygen atoms escape in the form of steam. By always filling your kettle up afresh, you are ensured fully aerated and tasty water."

Frankly, I can't find anything else anywhere that has evidence of such a claim.....more like the boy who cried wolf or one of grandmother's tales.

Most grandmother's tales come without any supporting evidence or reason for their sayings or claims, however, it is notable that many of their claims are useful hints to live by and also very interesting to analyze in.