Tizzite:
The final decision is yours. You don't say how big your Nano is going to be or what supporting equipment (filter, skimmer, etc) comes with it or how much time you want to spend with the maintenance of it. If it is small (under 29 gal) then I suggest at least getting RO water from HEB, Walmart, or the many little kiosk set-ups that are now all over the place. If you do decide to use tap water, then at least add a water filtration unit to what ever sink is going to supply it. Or look into getting a small RO/DI unit to put under the sink. To be honest, even one of those Brita units would probably be better then straight tap water. Finally read the past posts on this site, reef central site, some of the sponsors sites, and afterwards as I said- the decision would have to be yours.
wayneb