I froze clean, clear water and when it melts in a glass of water there are white particles. What is it?!

I froze clean, clear water and when it melts in a glass of water there are white particles. What is it?

Ok, I have even tried freezing bottled water in a clean ice cube tray and then letting the cubes melt in a clean glass of room temp bottled water and there is still white particles floating around in the water. I have also frozen a sealed unopened bottle of water and found there to be particles floating in it after its melted. I haven't tried distilled water yet but I think I'm almost curious enough too until I find out what that white stuff in my tap and bottled ice water is.

Almost all drinking water, bottle or tap has a small mineral content and sometimes even organic matter in it. Many bottlers such as Desani even add minerals for taste.
Don't be concerned as freezing water causes these to clump together, or floc. When the water is melted, they remain together.
No drinking water is pure H2O. A human would not do well healthwise drinking pure H2O. Your body needs most of these and the rest are harmless.

EDIT: as David H mentions below, distilled water is a very pure water, devoid of most impurities. It is the type of water you would want to use in a steam iron or for adding to older style batteries. You can use it to make crystal clear ice cubes but that could get pretty expensive compared to tap water.