There are quite a few trace elements which tap water provides. Dehumidier water is void of these elements. The "plus" in Cal / mag plus is most of these trace elements. The difference between distilled and dehumidified is that in a dehumidifier more trace elements are normally left behind by the precipetation process. Some of the water vapor collects and drips off of the coils and back into the tank. The process for distilling water is more efficent. Almost none of the minerals (trace elements) are left behind.

I understand what Zandor is saying I guess when I try to answer questions I don't really think about it from a practical stand point sometimes.

Herbus