From Flyin Dutch
Few questions:
Q: How often does your car engine stop due to water contamination as a result of condensation in a non full tank?
A: Never.
Q: Can I fill up an empty metal container with water by leaving it in a hangar for a few days and nights?
firstly car engines dont stop due to water contamination probably because they generally have water seperators in them nowadays as said by yorks. This is an innovation which has sadly not been adapted to GA engines in general.
Secondly you will never fill a metal container with condensation by leaving it in a hangar because it is not a sealed environment like a fuel tank, the water is able to evaporate out of it once the temperature rises again. A fuel tank not only traps the water inside once it condenses, but due to the fact that it is vented and not air tight extra moisture is able to get in over time.
Overnight the amount of moisture you are likely to encounter is minimal although it still warrants draining. But if the plane isnt used over a period of time then you would be surprised at the amount of water you can find.
just my two cents..
Zepth