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I was talking with a Scientist friend over the weekend. He said distilled water is just that... distilled water - no matter where you purchase it. Distilled water bought in one store is no better than distilled water bought in another.

ems wrote:I was talking with a Scientist friend over the weekend. He said distilled water is just that... distilled water - no matter where you purchase it. Distilled water bought in one store is no better than distilled water bought in another.

I am a scientist also. In theory, what your friend says is absolutely true, but in real life, there can be a huge difference between theory and practice.

A steam distillation process should produce pure water. But what if the apparatus cools between cycles and you have damp pipes sitting there with mold spores in the air? Or, what if the person charged with disinfecting/maintaining/cleaning the equipment doesn't do it perfectly one day? Or, what if a batch of the empty bottles that the pure water is decanted into for sale isn't totally clean, or the capping machine has a mouse nest in it... you get the idea. Mistakes shouldn't happen, but they can and do.

And having gotten interested in this question through my recent experience, I did some checking - most bottled distilled water doesn't even claim that it is sterile, and by manufacturing standards, it doesn't have to be. The containers are not sterilized, and it is not required that they be.

It turns out that there are products that are "Sterile Distilled Water" and they say so on the label. If it doesn't say sterile, it isn't sterile.

From the bit of checking around I did over the weekend, sterile distilled water seems to be available in pharmacies, but I didn't find it in any grocery stores. It's a lot more expensive than plain ol' distilled water, so for a person who has no problem with their usual distilled water, it's probably not worth it. But for anyone with, say, serious allergies or immune system issues, it might well be worth the added peace of mind.

I think the take-home message is that distilled waters from different manufacturing lines can potentially have differences due to the factors above, and switching brands is a very low-cost thing to do to see if it helps with a sneezy/itchy/drippy nose.

A better question is what can be carried by water vapor? It has been said by many people that virus can not be transmitted from water to vapor. I wonder if that is completely true and what about spores like mold?

RocketGirl wrote:If it doesn't say sterile, it isn't sterile.

Maybe, maybe not. If it's not labelled sterile then it isn't certified or guaranteed to be sterile, but that does not mean it is, in fact, not sterile. My veterinarian brother said one time that ordinary paper towels, particularly if they were individually wrapped, were sterile and perfectly safe to use for animal surgery. But they are not labelled, and therefore not guaranteed, to be sterile, so there is a remote possibility that some may not be sterile. When you think about the massive amount of material that moves through a manufacturing process, or a bottling process, it should be fairly easy to fathom why the end product would be sterile. There's very little likelihood any contamination, if it does get into the system, will stay in the system for any significant length of time as it will get flushed out by the passage of the material. I'd be willing to bet that 99.99%+ of bottled water is sterile, even when not labelled as such.

Sterile is a medical term of art. Distilled water, like drinking water, is not typically sterile. However, there are still of regulations and practices that guarantee the safety of such water. Outside of a medical setting, few things are sterile. If you clean your dishes and let them dry, you're clean dishes are not "sterile."

RocketGirl wrote:

ems wrote:I was talking with a Scientist friend over the weekend. He said distilled water is just that... distilled water - no matter where you purchase it. Distilled water bought in one store is no better than distilled water bought in another.

I am a scientist also. In theory, what your friend says is absolutely true, but in real life, there can be a huge difference between theory and practice.

A steam distillation process should produce pure water. But what if the apparatus cools between cycles and you have damp pipes sitting there with mold spores in the air? Or, what if the person charged with disinfecting/maintaining/cleaning the equipment doesn't do it perfectly one day? Or, what if a batch of the empty bottles that the pure water is decanted into for sale isn't totally clean, or the capping machine has a mouse nest in it... you get the idea. Mistakes shouldn't happen, but they can and do.

And having gotten interested in this question through my recent experience, I did some checking - most bottled distilled water doesn't even claim that it is sterile, and by manufacturing standards, it doesn't have to be. The containers are not sterilized, and it is not required that they be.

It turns out that there are products that are "Sterile Distilled Water" and they say so on the label. If it doesn't say sterile, it isn't sterile.

From the bit of checking around I did over the weekend, sterile distilled water seems to be available in pharmacies, but I didn't find it in any grocery stores. It's a lot more expensive than plain ol' distilled water, so for a person who has no problem with their usual distilled water, it's probably not worth it. But for anyone with, say, serious allergies or immune system issues, it might well be worth the added peace of mind.

I think the take-home message is that distilled waters from different manufacturing lines can potentially have differences due to the factors above, and switching brands is a very low-cost thing to do to see if it helps with a sneezy/itchy/drippy nose.

Yep, this is why I bought a home distiller--a very simple, easily cleaned stainless steel system. Each of those variables you mention can result in store-bought distilled water that is contaminated in some way. At any rate, I'm just more comfortable with my own "brew."

The home distiller we have takes two hours or so to make a gallon of distilled water
at a cost of 16-22 cents, depending on winter or summer electric rates here.
It is noisy, but luckily it runs unattended when we are out.

kong wrote:If you clean your dishes and let them dry, you're clean dishes are not "sterile."

The same goes for leaving you cpap gear out to "air dry". Or transferring your DI to 'another' container. Or using a funnel when filling your humidifier.

ALL which trap or transfer contaminants along with the water.

I still think that people mean well when they 'clean' their equipment using tap water which can contain the bacteria they are most worried about preventing.