Turn the water supply off and let the faucet run until the water lines are empty. Under the sink, the faucet is connected to the hot and cold supply lines. Unscrew the connections and drape the supply lines into the bucket to catch any water remaining in the pipes. You may need channel-lock pliers to unscrew the connections if they are on tight. Clean and discard any old Teflon tape that may still be on either the faucet or the supply line connectors.
Unscrew the plastic nuts under the sink that hold the faucet to the sink and take off the old faucet. An O-ring should be between the plastic nuts and the underside of the sink. This is often the part that fails.
Clean the sink where the old faucet was as debris can cause a bad seal and allow water to seep under the faucet and into the cabinet below.
Attach the new mounting plate to the sink and tighten until snug, but do not apply too much torque as this may break the thread or crack the faucet and sink.
Apply the plumber's tape to the threaded ends of the water lines on the new faucet before inserting it through the mounting plate. Trying to do this under the sink is difficult because of limited space.
Place the new faucet into the correct holes on the mounting plate. Screw the O-ring and the plastic nuts that came with the new faucet onto the faucet and tighten with the channel-lock pliers. Apply just enough torque to create a seal with the O-ring
Attach the supply lines to the faucet, making sure to connect the hot supply line to the hot water line in the faucet and the cold supply line to the cold faucet line. Tighten with the channel-lock pliers. Turn on the RV water supply and open the faucet to test for leaks.
