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Is Drinking Distilled Water Dangerous? November 9, 2008

Note: I'm not a doctor, zealot, or trying to sell anything - I'm just a regular guy summarizing all the research I did on this topic.
There seems to be a lot of controversy about what kind of water people should be drinking and cooking their food with:
The controversy is about the good & bad components in water. There are a number of good minerals found in "mineralized" water sources including:
There are also a number of bad components that might be found in water ( whether its bottled or not )
There is a wide range of waters, in terms of purity. On the one extreme is distilled water, which should contain absolutely nothing but H2O. On the other extreme is "hard water" which contains a large amount of minerals (and possibly chemicals). There are many types of water in between, some that have only a small amounts, or just a subset of the minerals in question.

The "total dissolved solids" (TDS) is a measure of how much stuff (typically good minerals) is in your water. Highly-purified water (distilled, reverse-osmosis, other highly-filtered) has a TDS well below 50mg/liter. Distilled water ought to have TDS=0. "Hard water" or mineralized water often has TDS > 200. The debate is about which is healthier: low-TDS water, or high-TDS water. Below are the common arguments that come up, and my take on them.

"Distilled/highly-purified water is missing essential minerals that your body needs."
The amount of minerals in normal water is very small compared to the amount found in food (less than 10%). A humorous thought experiment mentioned here was to imagine a blender with a day's worth of food and consider the tiny difference in minerals between adding distilled water to this, or regular water. However, some argue that the calcium/magnesium/etc... in water is more easily absorbed by your body than from food or supplements.
I think this may be more important of an issue if you are already low on these minerals, and don't get enough of them from other sources (eg. eating nutritious food, cooking with tap water, drinking other liquids like orange juice, etc...)

"Purified water can "leach" metals and other bad chemicals from the pipes and containers."
Apparently, pure/low-mineral water is chemically "unstable" and wants to dissolve away the materials around it. If you store your (pure) water for a long amount of time, or get it through pipes that haven't been setup to do so, this is something you should think about.
Overall, this is really a contamination issue though, not about how distilled water affects your body. I just wanted to mention it for completeness.

"Purified water leaches vital minerals & ions from your body."
It stands to reason that if you drink distilled water, and urinate any of these vital minerals, that there is a net loss. I get the impression that the dissolving/extracting power of distilled water is very high, and that drinking it will draw out many good chemicals (in addition to the bad impurities) from your body. Perhaps distilled water is less dangerous when drank with a meal? I've read claims that distilled water is particularly bad during exercise (presumably because that is when your body needs those electrolytes the most).
Frustratingly, there doesn't seem to be much research on this. Would it be that hard to measure the amount of these chemicals in the urine of distilled water drinkers compared to normal?

Then why do people drink distilled water?
I understand the inclination to avoid tap water (that's a whole controversy of its own) - but good bottled water can achieve this goal. As far as taste, this is a personal matter, but presumably everyone could find a non-distilled alternative that they like (as I am going to do now) for drinking on a daily basis. If you have a particular need to remove impurities from your body, I think distilled water is safe & effective in doing so, understanding that it may remove good materials from your body as well. I've also read that activated charcoal has been used for the same purpose.

So, what water should I be drinking?
I have no idea :) How ironic is it that modern man cannot answer such a simple question, when drinking water is something that every life form on Earth was born from?
If you believe all the evidence in the references below, you should be drinking water with a high TDS (lots of calcium, magnesium, and other good stuff), that doesn't have toxic metals or chemicals.
There doesn't seem to be any specific health benefit from distilled water except for avoiding bad chemicals. From what I've read, the only "danger" with drinking reasonable amounts of distilled water is the long-term mineral-deficiency it might cause in your body. But maybe our Western diets & lifestyles are already so deficient in these minerals that distilled water exacerbates it?
There is also a lot of controversy about whether alkaline water (pH > 7.0) is generally better for you because it helps your body be less acidic (which is the source of most disease according to alkaline-diet proponents). I hope to research this more and post later about it. But one point worth noting is that supposedly distilled waters are actually slightly acidic because they readily absorb CO2 from the air (carbonic acid).

As I find out more about various bottled water, I'll post them here. For starters, you might consider:

If you have a brand of water that you swear by, please comment on this post.

Further reading:
http://www.who.int/water_sanitation_health/dwq/nutdemineralized.pdf - a great report by the World Health Organization citing a lot of research on why water-without-minerals is unhealthy
http://www.cyber-nook.com/water/distilledwater.htm - a page with lots of information on both sides of the issue
http://www.mgwater.com/calcium.shtml - a research paper showing that "hard water" was correlated with lower rates of cardiovascular death

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