Yes, ingesting tinsel could be dangerous and the water might not be ideal, but I (for one) wouldn't worry about it too much. Princess Kuhio drank water from the Christmas tree every chance she got for 17 years. She also drank from the ditch behind our house the soapy runnoff from the guy washing his car down the street and the toilet. The kittens probably won't drink much of the water. They are just curious.