Yes you can put it in tap water. I seem to recall that you should not use distilled water, though. Prill beads are supposed to make tap water taste much better and become cleaner, lighter and more pure. However, I have read in some places on the internet where a couple of people did not have good luck with it because their tap water was so bad to beginn with. I bought Prill beads about a month ago and have been using them since. The water's very easy to make. My husband and I have done "taste tests" using 1) tap water, 2) charcoal-filtered water (with a Brita filter-pitcher), and 3) Prill water. They all taste different. He thinks the Prill water is "oilier" or heavier, although it's actually supposed to make water lighter. I filter the tap water in a Brita pitcher because we have a lot of chlorine in our water supply. I am giving the water to my houseplants and my cats too. Don't know yet if it's doing me any good, although I was already in pretty good health. I got my beads from www.thewolfeclinic.com, they were about $20. You can read all about them there. What the heck, give them a try!