Re-Plumbing a Kitchen Sink
Turn the water valves underneath the sink counterclockwise to turn them off. If you cannot find the valves underneath the sink, find the main water line and turn off the valve there. Using the adjustable wrenches, turn the nuts connecting the faucet lines to the hot and cold water pipes underneath the sink. Use a bucket to catch any water that drains from the faucet lines after they are disconnected.
Turn the nuts on the hot and cold waterlines that are connected to the faucet counterclockwise with an adjustable wrench until they're loose. Use your fingers to turn the nuts the rest of the way until they are completely removed. Place the faucet lines in the bucket.
Remove the PVC piping that connects the wash basins to the water drain. Turn the large plastic nuts counterclockwise on the basins to remove them. Disconnect the PVC drain pipe from the water outlet located on the wall by turning the large plastic nut counterclockwise. Remove the disconnected PVC pipe from underneath the sink.
Clean the threads on the water valves and hot and cold fittings on the faucet using a wire brush. Remove the old pipe tape and residue that has built up over the years. Dry the threads with a clean rag and install new pipe tape on the water valve fittings and the hot and cold fittings on the faucet. Wrap the pipe tape around the threads until they are completely covered, about two to three times around.
Install the hot and cold water-lines onto the faucet connections by turning the nuts on the end of the lines clockwise until hand-tight. Use the adjustable wrench to turn the nut until it can no longer be turned. Connect the other ends of the water-lines to the water valves. Turn the nuts clockwise until tight, then use the adjustable wrench to turn the nuts until they can no longer turn.
Cut the new PVC pipe to the desired lengths using a hacksaw. Re-connect the drain tube to the wall by turning the large plastic nut clockwise until tight. Install the PVC pipe onto the wash basins underneath the sink by turning the large plastic nuts clockwise until tight. The large plastic nuts only need to be hand-tight. After the PVC piping is re-installed, turn on the hot and cold water valves.