When all else fails, use a tree.
When all else fails, use a tree.
Those plugs work for the hull of a boat, why not a drain line? 
Sometimes I see this,
Thanks to ‘non-pressurized’ plumbing drains many “sins” can go undetected for years !!
Mario, I think that’s a water stain at the end of the wood plug there. It is starting to rot…
