My first suggestion would be for you to look at a working
CP bog (artificial) such as the one found at the NC Botanical
Garden.
Your tap water *may* be acceptable for use in a bog especially
if it derives from a well source and not a municipal system.
RO water is water purified by reverse osmosis, which removes much
of its mineral content.
This past winter was a bad one for NC, but is a good one to gauge your
insulating needs. The folks over at Gnome Nest nursery got a large
number of Flytraps from the now defunct Hungry Plants. They overwintered
under a light mulch of pine straw in a protected location even though
our low temps went to 0 F.
I'm just up the road from you so e-mail if you need directions to any
of these places. Take care!
Jeff
welch@niehs.nih.gov