The water stain is growing. You've investigated the problem and find the leak coming from the joint of a PVC pipe. You have two options: pick up the phone and call a plumber who charges $80 to knock on your front door or spend a few hours and tackle the problem yourself. A leak in the joint of a PVC pipe is a small problem that can turn into a major issue if it isn't addressed quickly.
Locate the leaky PVC joint. Ensure that all piping to and from the joint is not damaged.
Measure the PVC joint and the surrounding piping. You will need the length, the joint's angle and the diameter.
Purchase a replacement PVC joint. The new joint will need to be extra long (approximately 2 inches longer than the original joint) because cutting out the damaged joint will lengthen the distance between the existing piping.
Turn off water to the entire house at the water meter. One line, the supply, runs from the water source to the meter and the other line runs from the meter to the house. Shut off the valve located on the supply line to turn off all water to the house.
Cut out the damaged PVC joint using a hand saw or chain saw. Each cut should be made where the joint and existing PVC pipe meet.
Clean and sand the edges of the new PVC joint and the existing pipe. Be sure to remove all glue and dirt.
Fit the new PVC joint to existing piping. Mark where the joint and pipe meet. Remove the PVC joint. This tests whether the new joint is long enough before applying the primer and glue.
Apply primer and glue to the inside of the PVC joint and to the existing piping. Fit together and let dry for the recommended amount of time. Turn the water to the house back on.