This has been going on since the end of July. We had black stuff coming from the bathtub faucet and it was intermittent. We have had the drain snaked professionally and then had to call him back about a month later bc it was happening again. He said it was prob some rubber ring deteriorating and replaced it. It’s been several weeks and I turn on the faucet tonight and here it is again. Any ideas? I keep paying out money thinking it’s fixed and it’s not obviously. I have no idea what it could be.