Hacker News Reader

Comment by jbotz | Hacker News Reader

I don't buy this, I think it's just an urban legend. Note that they provide no references for their claims.

I heard similar claims about drinking distilled water decades ago, and determined that they were BS by self-experiment. Now, it does make a certain amount of sense that ion-free water could be problematic for biological systems, but distilled water is already close enough to ion-free (with respect to a typical biological system, which in some sense is just "very dirty water") that I can't see how further purification could possibly suddenly tip it from "just fine" to "so toxic it will kill a goldfish in seconds". In fact, form a biological perspective even rain water is pretty close to ion-free.

View on HN

So I have lived this experiment. Back when I lived on a submarine in the US Navy, when we went out to sea for several months at a time we made all of our own drinking water and I was the person who ran the distillation plant. When you run the plant almost continuously for months straight in the open ocean, it produces cleaner and cleaner water as the plant's essentially continuously flushing itself. After several months, the water in our potable water tanks would pass all the tests to be pumped straight into the nuclear reactor. All the scum that grew inside the potable water tanks would slowly die, as it had no nutrients to live off of. So the whole crew was drinking Type 1 pure water. When new people came onto the boat mid-deployment, they would often get diarrhea, but they'd acclimate and they'd be fine after a few days. That is my (unscientific) eye-witness first-hand lived experience. I wouldn't be surprised if a fish were very unhappy living in pure water, but I seriously doubt a fish would die in ten seconds.

Very interesting. Any idea how pure water could cause diarrhoea?

It might have been the food?

guessing the sudden imbalance of salts between the body and the incoming pure water would cause some reaction, maybe it triggers some sort of 'poison' response? that would cause vomiting too though

Would love to hear more about your experiences in a blog post

> I can't see how further purification could possibly suddenly tip it from "just fine" to "so toxic it will kill a goldfish in seconds"

First of all plopping a gold fish just like that into a new tank sounds bad. It is possible the temperature shock killed it.

My other guess would be the lack of oxygen. Ultrapure water used in litography is degassed to prevent the formation of small bubbles. No gass, no oxygen, that can also easily kill a fish.

The temperature might well matter :-) My minds eye has a picture of a goldfish lithobraking into a wall of solid ice.

Right. Ultra-pure water is, indeed, extremely pure ... but even tap water is already very pure by the standards of blood, or intra/extra-cellular fluid. The difference between UPW and tap water is nowhere near enough to make it dangerous to drink, save in quantities that are already objectively dangerous to drink tap water: osmotic pressure depends on differences in concentrations, not the absolute level of purity.

I think I agree with you that distilled/ultrapure water wouldn't be harmful, but I think it would be okay only due to consuming electrolytes in food. I bet the amount of salts/minerals you need in food increases if you only drink distilled water. And I bet if you fast and only drink distilled water, you would eventually get sick/die.

Reply on news.ycombinator.com