Last month our basement got flooded and I had to tear down all the drywall and remove plastic shower pan as the water got underneath everything. To stop future flooding we are installing an overhead sewer system. During the process the inspector pointed out that the shower drain was not vented. At this point I don't want to spend any more money to fix the downstairs plumbing. What can I do to cap off the drain? I live in one story brick raised ranch just north of Chicago.