[andyauger]

Heat up an electric hot plate, take a couple of drops of the oil on your finger, flick it on the plate. If there's water in the oil, even emulsified water, it will pop and crackle.

 

[andyauger]

Yep, no water. Emulsified water will often not settle out no matter how long you wait, so the crackle test (really, it's a real lab test) is used to detect water.