Hi All,

First time here, I have found a problem with my horizontal 3" copper drain pipe near the exit of the home to septic tank. (3" line runs into an elbow, then down around a foot to the exit pipe that runs to the septic tank).

Was removing my ceiling tiles - and noticed some green debris and a little bit of evidence (now dry) of green leakage. The bottom of the 3" pipe looks and feels solid. I noticed the growths of copper (& something more?) coming out the very top of my pipe. Internet research seems to indicate these DWV Copper drain pipes fail at the bottom - not the top. I'm guessing it's a gas issue from the septic tank? I've not been able to find any images that come anywhere close to what I'm seeing on my pipe.

Looking for concurrence on what happened - and solutions. I want to avoid replacing the complete pipe, as it has 4 unions near the center of the home. I could 'easily' replace the 6-7 feet of pipe from the last union to the exit elbow.

Check out the pics!!

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I am not sure just what caused it, but since it is NOT on the bottom, it is probably not a "flow" or water problem. I cannot imagine any repair other than replacing the pipe. What kind of "unions" are in the pipe?

Hey hj - you wrote:

>>Author: hj (AZ)<<

>>I am not sure just what caused it, but since it is NOT on the bottom, it is probably not a "flow" or water<< >>problem. I cannot imagine any repair other than replacing the pipe. What kind of "unions" are in the pipe?<<


There are 2 3" tees that are brass/copper and 2 other brass/copper Y-joints that have either 1 1/2" or 2" pipe inlets. Would prefer not to get into converting these T's and Y's over to PVC if possible. At the opposite end of the pipe (adjacent to the final 3" tee) there is a screwed-on clean out cap/plug. The whole horizontal run (with the tees and Y's) is approximately 18 feet long.

Those are connections, not unions. Normally, all pipes in a system are the same age and quality, so I don't hold out much hope for any of your copper drain lines.

Hydrogen sulfide gas is acidic and will cause the deterioration of the copper pipe. The upper section of that horizontal pipe doesn't get washed "clean" and the condensation that builds up along the top of the pipe can concentrate the hydrogen sulfide, causing the rot. Vertical pipes are not going to be as susceptible as horizontal pipes. If the problem is from hydrogen sulfide gas, a house trap will keep the gas out of the house piping.

Thanks for the reply. I cut out ~5 horizontal feet of the drain pipe, and found thinning at the top for this distance. The pipe that I left had no thinning (and was amazingly 'clean' for it's age). Question on the whole house trap recommendation - how does the vent pipe play into preventing the gas build up? I'm guessing that the vent is supposed to allow the septic tank gas to evacuate the overall system? Does my issue perhaps mean that there's an issue with the vent pipe?

Thanks again for the knowledge and advice.