If there is a puddle forming where it's not supposed to be, chances are you need to replace the angle stop valve. Following the steps below will aid you in replacing the valve.
Step 1 - Turn the Water Off
Turn off the water from the main shutoff.
Step 2 - Disconnect the Supply Hose
Next you will want to disconnect the water supply hose from the top of the angle stop valve by turning it loose with your pliers. Take off the retaining nut to loosen the valve.
Step 3 - Remove the Angle Stop Valve
Now take the angle valve off. Using pliers, take the compression ring off the end of the house pipe. Then remove the retaining nut as well.
Step 4 - Install the New Retaining Nut
Put the new retaining nut over the house pipe. Place the compression ring over the end of the pipe.
Step 5 - Wrap It Up
Wrap your plumber's tape around the threads and tighten the nut.
Step 6 - Connect the Water Supply Again
Connect the supply line to the taped stop valve. Use pliers to tighten it securely.
Step 7 - Turn On the Water
Turn the water back on and test your work.