Well water is actually a chemical, so i think it might be difficult to perform an extraction without at least a few chems. There is a
water only tek but as far as i know there have been only poor results besides from the creator of the tek. I think what you may be looking for is a
food safe tek like what JilPil mentioned.
I find that as long as you are careful with your procedure and have clean solvents, a really safe product may be made. You have to be really sloppy to take any base soup along with your NP solvent. It's up to you though, buddy. If you feel safer and happier to use Calcium Hydroxide and Limonene (orange oil), then by all means go for it! Limonene is really expensive where i live, so i stick to what i can get. Good luck!