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Water Filters

Spent yesterday evening reading about how water filters work. This is probably all over simplified and I'm probably missing the point dramatically, but:

A lot of what they do is, using a special resin, they perform ion exchange in the water. Removing calcium (and other) ions and replacing them with sodium ions. Hence why filtered water tastes salty.

What I don't get is the fact that supposedly we're supposed to eat more calcium because a lot of people don't get enough (strong bones and all that) and we generally eat too much sodium already and are supposed to cut down.

In which case I can understand the use of one for say the glasswasher we have at work where it stops watermarks on the glasses, but for drinking water? Why? What's the benefit of it?

I know in the USA they do something similar with their wine exchanging potassium for sodium to stop the formation of tartrate crystals, but it's illegal to import wine into the EU that's had done to it. Hence, it doesn't find it's way over here... in theory.

Comments

( 8 comments — Leave a comment )
emperor
19th Dec, 2005 09:41 (UTC)
You shouldn't drink too much filtered water, actually. It's really meant to be used for hot drinks and the like, where it won't furr up the kettle.
hmmm_tea
20th Dec, 2005 01:09 (UTC)
It's really meant to be used for hot drinks

ooo, lovely, salty tea!
yellowrocket
20th Dec, 2005 19:16 (UTC)
Kettle fur can be avoided by putting a sea shell in the kettle (no, really! The limescale is more attracted to the shell than to the element so you end up with a furry shell and a cleaner kettle. It's not perfect but it is an improvement)

I too prefer my tea non-saline...
liveavatar
19th Dec, 2005 09:46 (UTC)
There's a few other types of water filters that don't switch out calcium for sodium, which might work for people who have sodium problems, especially activated carbon filters (like Brita, which I just started using), or reverse osmosis filters (more expensive, often needing installation and not just a pour through a pitcher).

Thanks for getting me to look this up, by the way. I'd been meaning to do that websearch for a while.
cartesiandaemon
19th Dec, 2005 11:09 (UTC)
Indeed. Except I will look it up in a bit...

And what *is* your icon?
liveavatar
19th Dec, 2005 23:23 (UTC)
Oh, it's X-rays beaming from a black hole in the heart of the Crab Nebula. Courtesy of andrieal.
cartesiandaemon
20th Dec, 2005 00:02 (UTC)
Ah! I looked at the caption, but andrieal didn't mean anything to me, I didn't realise it was a person[1]. Thank you.

[1] Typo: parson.
hmmm_tea
20th Dec, 2005 01:10 (UTC)
And what *is* your icon?

It's the little picture that appears above the name in the comment.
( 8 comments — Leave a comment )

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