Originally Posted By: rcloyd This post was automatically imported from our archived forum.
Rafael:
When copper oxidizes it turns green. You may have agressive water that oxidizes the inside of your copper pipes and leaves the stain on your sink.
A couple of suggestions:
1) have your water tested to determine if it is agressive to copper. If so you may need a water softener system.
2) Test the soldered connections of your copper pipes for lead content.