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Nasty Film in Sink Drain

We have double sinks in our master bath. Every now and then the one on the right has the drain slow down. I have to take apart the drain from the stopper in the bowl, to the pipes under the sink, to the connection to the drain line into the wall and for lack of other description, a nasty black film that is on the inside of the pipes, up to 1/4 inch thick in spots. The large chunks come off fairly easy, but it is hard to completely remove the material. It is almost a rubbery, slimy substance. First, what is it? Second, why does it only happen in one sink in the same bathroom (In the 8 yrs we've been in the house)? Third, how do I get rid of it?

Thank you!

Re: Nasty Film in Sink Drain

The only thing that can get into the drain is something you put into it. The reason it's only in one sink and not the other is more then likely there are two different people using the sinks. In most cases it would be you and your wife. One of you is using something the other isn't.


Re: Nasty Film in Sink Drain

It's mostly soap scum, which is a byproduct of a rather complicated chemical process when soap is used in acidic or mineral-laden water. Insoluble compounds are produced, which then bind to the trap as the water sits. The blackness is from mold growing in the soap scum (yuck!). Many bar soaps contain talc, a mineral, so, therefore, they form scum. The higher the talc content (and possibly the lower the glycerin content), the more likely you are to see scum buildup.

Note that shaving cream may also contain soap. I don't know how the composition compares to bar soap.

About.com: How Soap Cleans

Re: Nasty Film in Sink Drain

Soap scum, spittle, and most generally plastic components in the drain. Plastics are a great medium for growing mold. You might try periodically pouring bleach down the drain. Bleach is great for dissolving organics.


Re: Nasty Film in Sink Drain

Thanks for the info so far; much appreciated!

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