Put some drops of water on a glass or plastic sheet. After evaporation we seesome white spots like dust over?
Try it with distilled water, you will get a different result. There are impurities in tap water.
And if you think that's gross, take a vial of ocean water and look under a microscope. We are NOT alone, there are SO many live things dwimming with us, bleakkssk!
If I'm not mistaken, these white spots are actually caused by dust and dirt in the air that were caught by the water, and they are left behind after evaporation.
These are dissolved salts ( other impurities) that remain behind when the water evaporates.
