We already learned how to make hard water, both temporary and permanent. Now we want to undo that.

In order to make hard water soft, we have to do something to remove the minerals, or to neutralize them.

To remove minerals from temporary hard water, all we have to do is boil it.

To neutralize the minerals in permanent hard water, we need to add either washing soda (sodium carbonate) or borax.

Let's soften both kinds of the hard water we made, and then test them, by dissolving soap in them.