Just checked the bag, it is coconut fiber. My wife got him as a gift for me and she called it "mulch" and I just ended up getting stuck calling it that. She talked to the pet store owners and they didn't say tap water was poisonous to them. I've been using tap for quite some time now. I don't have a water conditioner, can I simply boil it to sterilize it and wait for it to cool down?