Reboiling water

[andiesenji]

So the upshot is that if Steven's water is inferior the second time around, it can't possibly have anything to do with dissolved oxygen, right? The only real possibility is if it has accumulated something from the pot itself, and using fresh water minimizes the effect?

I don't think that's the upshot at all. I think the upshot is not that Steven's water actually is inferior the second time around. I think what he's saying is that he doesn't actually reboil water because he has the idea that it would be inferior the second time around.

New York City tap water is better quality than most bottled water, especially if you have removed the small amount of chlorine used (either by filtration or by degassing through boiling). More to the point, it is naturally very soft water. So it's pretty much impossible that his kettle would concentrate enough dissolved solids to produce a negative taste effect unless he never ever emptied the kettle and rinsed it out. Even if he always only used half of the water and always replenished the kettle without ever pouring out all the water, it would take many, many kettles of half-reboiled water before the nonvolatile substances approached the concentrations that many parts of the country consider normal.

Well said! - or written!

[nickrey]

Seems the water is great at the source and in the intermediate delivery system. There must be some old plumbing though: even the water board acknowledges this is a source of contamination. This stuff gets into kettles and creates scale. See my comment above.

[slkinsey]

Scale comes from "hardness" in the water -- i.e., calcium carbonate, calcium sulfate, and magnesium hydroxide. This is not something that is going to be picked up out of old plumbing. Yes, I suppose if Steven always replenished a half-full kettle and never ever emptied it, it would eventually concentrate enough minerals to scale. But this is unlikely to happen. Most of the time with ordinary use of a kettle it is emptied every so often. The point is that there's not much use of emptying it every time, because replenishing the kettle rather than filling it with fresh water isn't going to make much difference with NYC tap water at least for 5-10 replenishments.

[Fat Guy]

If slkinsey is right, and it sounds like he is, then I have wasted about 50 million gallons of water in the past couple of decades.

[gfweb]

You and my wife. She insists that once-boiled water is no good. This despite tons of science education and my own rational discussions invoking past chemistry courses and common sense.

[Emily_R]

So glad to read this thread, so I can stop wasting water -- I've also been in the camp that somehow heard that reboiled water wasn't as good. That said, I have really hard water, so it may be time to give my kettle a good descaling...

[Simon_S]

I'm pretty sure I read an entire discussion about this in one of those New Scientist Last Word books, but I can't seem to find it online. The premise there was that tea made with twice-boiled water tastes differently, and people attempted to explain why.

In truth, I don't notice the difference myself and I drink a fair bit of tea. It still doesn't stop me boiling a fresh kettle every time.

[slkinsey]

FWIW, I have used the same copper "whistle top" kettle for around 15 years. I replenish if there is water in there from a previous boiling, but it's also not uncommon that my usage empties the kettle. It's quite easy to see inside the kettle, and there is clearly no appreciable scale.

It seems pretty clear that this idea grew out of places where the water had a high mineral content (in which case reboiled water probably would taste worse than the already not-so-great-tasting fresh water), and then turned into an old wives' tale that spread to parts of the country where it didn't make any sense. There are plenty of parts of the country where even a single boiling of the water will leave a small amount of white scale on cookware.

Edited October 24, 2011 by slkinsey (log)

[DanM]

I use a reverse osmosis water filter and never notice a difference between boils.

I guess we can make an experiment out of this. If someone wants, you can fill a kittle with 1 litre of water, bring it to a boil and pour off 100ml. Return the water to room temp and repeat. Once you have enough samples, taste the water to see if you notice any difference.

Dan

[nickrey]

I grew up in Adelaide, South Australia, driest state on the driest populated continent. Reputedly one of two places in the world where ships would not fill up their ballast water (the other being Aden). One boil would be enough to scale a kettle for a lifetime. I envy you New Yorkers your wonderful water.

[Mjx]

There might be a difference between freshly-boiled and reboiled water, and up to a certain point, I acted as though that was the case (never tested it, however), but then decided that the difference was unlikely to be significant enough to justify my wasting water by pouring it away.

[Ashen]

It is very unlikely that I would ever notice a difference even if there is one. I do often drink tea in the winter , but it is bagged black tea brewed strong , and then I bruise it.. (I wring that teabag for all its worth) Then add a good hit of lemon and honey. It is a decent fairtrade organic ceylon black tea though.

[Kent Wang]

FWIW, I have used the same copper "whistle top" kettle for around 15 years. I replenish if there is water in there from a previous boiling, but it's also not uncommon that my usage empties the kettle. It's quite easy to see inside the kettle, and there is clearly no appreciable scale.

It seems pretty clear that this idea grew out of places where the water had a high mineral content (in which case reboiled water probably would taste worse than the already not-so-great-tasting fresh water), and then turned into an old wives' tale that spread to parts of the country where it didn't make any sense. There are plenty of parts of the country where even a single boiling of the water will leave a small amount of white scale on cookware.

 

I live in London and the water is pretty hard and leaves scale everywhere. But why does reboiling result in worse tasting water for tea?

[Naftal]

Hello- This thread also has an interesting, and long, discussion on whether or not boiling causes water to lose oxygen (and thus making poorer tea).

[andiesenji]

Three years ago when this thread first appeared I wrote extensively about my experiences with brewing tea from three different hot water sources.

 

There was no discernible taste in the tea from the Zojirushi water boiler that had been filled at least 3 hours earlier and was set to boil the water and then hold it at 205°F., the water from my InstaHot at the sink and freshly drawn water boiled in a kettle on the stove.

 

Water can absorb oxygen just by being poured - "agitation" - and with bubbles forming and breaking while it is boiling. 

 

I have British friends who grew up drinking tea brewed with water that had been heated in large urns and held at near boiling for hours.

They laugh at the notion that reboiling water causes it to taste bad.  UNLESS THE WATER IS AWFUL TO START WITH.

There are excellent filter systems now available that remove chlorine and other chemicals from tap water and if that is used there is no reason to waste water that has been boiled. 

[Mary33]

You and my wife. She insists that once-boiled water is no good. This despite tons of science education and my own rational discussions invoking past chemistry courses and common sense.

Really like my mum! It is impossible to prove something to her!  And she insists on boiling only fresh water!