Re: Why did my unopened bottle of distilled water implode?

I use distilled water in my humidifier in the winter, and I have experienced the same phenomenon if I store jugs for a long period of time. I think I know the answer, but I have not ever investigated it in excruciating detail, so I do not offer the following as 100% true.

I stumbled onto what I think is the answer once when I took the top off a jug that had a certain amount of "shrinking". As soon as I removed the top, a very small, pinhole-sized, leak showed itself in one bottom corner of the jug. The hole was not big enough to allow water to drip out when the jug's top was still on, but when the top was removed the negative pressure in the jug was equalized and so the water could drip (very slowly) out. See the next paragraph for an explanation of where the water went over the long storage period.

I used the term "negative pressure" above. What I think is happening is that the water very slowly evaporates from the pinhole in the jug, and as it evaporates the pressure in the jug is reduced very slightly. Over a long period of time enough water evaporates that the jug's being squashed by the surrounding air pressure makes it obvious that something has happened. It is the small negative pressure that helps keep the water from dripping out when the top is still on the jug.

So, I think the water is very slowly evaporating through a very small hole in the jug. Jugs without holes store the water okay. I have successfully stored water for over a year in intact jugs.

John Link, MadSci Physicist