My 2nd floor bathroom sink keeps filling up with black mold. All along the insides of the piping and all over the drain plug. I have removed the plug and scraped the walls with a bleach soaked bottle brush. Also soaked the plug in a galss of bleach. Have also poured bleach down the sink but this does not help and the walls don't "soak" in it. I've been doing this for years and would dearly love to be rid of this problem,
Answer:
You'll have to dis-assemble the drain and clean it off as well as possible and that should look after most of it.
