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Plumbing in the Home/Black gunge in basin outflow pipe


I have in my upstairs bathroom a basin with an all plastic outflow pipe with the usual U shaped trap.  Whe I open this trap I find it contains a build-up of black gunge, partly gel-like and partly hardened onto the inside of the plastic pipe.  I clean this away, but it soon builds up again.  What causes this and how can I stop it?

Dear Terence,

    The black gunge which builds up there is normal...  it happens when body oils, grease, soap, shampoos, etc... cling together and adhere to the inside of the drain pipes.  It can develop to a point where it can clog things up and cause a stoppage.  Normally though, bacteria inside the drain system break down this stuff and allow it to be washed away.

   In your case the buildup is happening at the point of that trap because of the standing water there... fatty oils float on top and then adhere to each other and to the pipe.  Any point where there will be standing water will be prone to this kind of buildup.  Unless it is excessive and causes a blockage it is unnecessary to clean it out, also the bacteria which are beneficial to keeping the system clean may also contain types which may be harmful to humans.... so it is not advisable to do this yourself.

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Thomas Ambler


I am experienced at troubleshooting and solving all types of plumbing problems. Issues related to specific manufacturers fixtures and specifications though are beyond my field of expertise. I have dealt with problems in both rural and urban areas, and with water supply and drainage systems. Plumbing issues can be very obscure... such as odors, stains or occasional seepage. I have even had to chase rats from a customer's sewer line.


I have 25 years experience dealing with plumbing systems (which also includes hot water and steam heating systems). My main expertise is in diagnosing and solving problems. I have worked in construction and installation of new systems but do not regard myself as an expert in that area.

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I completed high school and one year of college. I served 4 years in the Marine Corps and have education in electronic and electrical troubleshooting and repair. I have attended classes on installing and repair of oil burners, and I have EPA universal certification for air conditioning and refrigeration. I am now enrolled as a full-time student at Everest college to re-train for a new career. Any donations of financial support would be greatly appreciated.

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All of Denny's Restaurants in NJ, Several Burger King stores, I have done work at two different homes for Bruce Springsteen. I have also worked for Jim Johnson (of J&J) and his family, Whitney Houston, Steve Forbes and many others.

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