Well most newts you're going to find are going to be fully aquatic or fully terrestrial (or seasonal. but most can be maintained year round in one type of enclosure). There are only a few species I would see using both regularly, yet might not. I would pick which type of enclosure you're more interested in and go on from there. Also, most newts dislike having any water flow, and most of the ones that like it are wild caught and are extremely hard to find captive bred.