An island sink presents a unique plumbing problem ... A second clean-out may be required in the vertical wall vent pipe. An AAV is a plumbing fitting that you can glue onto the drain pipe.

If you have CPVC (plastic) or steel pipes, add tee fittings made of ... then open the sink faucet and another lower-level faucet to drain the pipe. Next, cut out a small section of the cold ...