- 1). Move everything out of the sink cabinet so you have complete access to the sink drainpipes. Position a bucket under the S-trap to catch the water still in the pipe. The S-trap, or P-trap, is the center pipe between the sink tailpiece and the sink drainpipe, connecting to the wall plumbing.
- 2). Loosen the two nuts that connect the S-trap to the sink drainpipes at both ends with a pipe wrench. Once the nuts are loose, turn them by hand until you disconnect the S-trap completely. Place the S-trap inside a bucket and allow any water left in the wall pipe to drain into the bucket.
- 3). Place the pipe wrench around the connecting nut that secures the wall drainpipe to the house plumbing and attempt to turn the nut counterclockwise. Most old house plumbing is cast iron, and rust accumulates in this area due to standing water in the pipe. Remove the pipe wrench if the nut does not turn.
- 4). Spray the outside of the connecting nut with penetrating lubricant and allow it to work for 15 minutes. Scrub the area between the connecting nut and the house plumbing with a wire brush. Remove as much rust as possible with the wire brush.
- 5). Wedge the jaws of the pipe wrench around the house plumbing connection from underneath it. This connection is usually a tee. If necessary, cut some of the drywall away from the right side of the connection with a utility knife. Gripping the house connection with the pipe wrench helps keep it from turning as you remove the wall sink pipe.
- 6). Position another pipe wrench over the sink drainpipe connecting nut and attempt to turn it counterclockwise. If necessary, hit the handle of the pipe wrench with a hammer to jar the nut loose. Continue turning the connecting nut until the sink drainpipe is free from the house plumbing.