Will your cat get sick if they drink water from a Christmas tree holder?

It depends what you put in your Christmas tree water and how your stand is built. My 12 year old cat has been drinking Christmas tree water since she was born and is still alive and kicking. However, we have never put anything in the water. This year, because we got our tree so early we bought some tree nutrients and have been adding it to the water. We also got a new tree stand so that the cats can not get into it and drink it as with the years before. I wouldn't want her drinking chemicals....