Indeed a great layout of the different types of water.

Maybe i read the thread not thoroughly enough.
But what i missed was a warning on this.

NEVER use pure osmose or distilled water on youre frogs for soaking purpose,
since it WILL kill them.
Because of the principal of reversed osmosis,
this water will extract minerals from you're frog to compensate the balance between the water in the frog and in the bowl.

There has been cases where people used purified water in order to soak the frogs for a treatment.
In a matter of minutes they will die because important minerals are extracted out of the animal.
ALWAYS mix it up with ventilated tapwater or rainwater to make the water less aggresive.
Same for people using any kind of automated rainsystems using metal spraying nozzles, the aggresive water will solve parts of the metal and spray this into you're tank.
Therefore, please use purified water with caution!