well, the problem I could see is if you do polish it, the chemicals it would release, not to mention the pipe it's self may leach heavy metals into the system. I would imagine that if you stay on top of your water paramiters, you should be fine. But I do not know. Give this thread a little more time to see if anyone else has more to add, you may just have brought up a great topic. I know for a fact people use PVC and clay very frequently. But metals, not so much.