Black valve outside house, what is this?

[Marc Ilgen]

IMG_1974

• Marc Ilgen
• Apr 26, 2019

I know this question will show my nearly-complete ignorance regarding plumbing issues, but here goes anyway. In the back of my house there is some sort of black valve/cap that is now leaking and starting to look a little moldy. What exactly is this? I don't even know what it is called much less what it is supposed to do. In any case, it is starting to leak and look a little nasty, as you can see. What should I do about this?

 

[havasu]

It is a clean out to allow professionals to easily snake out your main line. If you are accumulating water there, you may have the beginning of a blockage in your line. Open her up, inspect, and if OK, put a light coat of plumber's paste to lubricate the threads, then tighten it up.

 

[Diehard]

Be prepared for a possible rush of messy liquid. Amount unknown.