Unless your gutters are clogged with leaves as is common in woodsy areas normal rainfall is likely the cause.
Bead of water along gutters.
The small amount of rain that falls on the rim of the gutter trickles down to the lowest point on the bottom.
On a rainy day inspect your gutters to see if the water is flowing smoothly through the channels and away from your home.
After that run a large bead of gutter sealant along the outside of the bottom of your spout.
Apply a generous bead of gutter and flashing caulk along the vinyl rain gutter seam.
Snap the sections of gutter together.
Surface tension holds these beads of water in place until the droplet becomes too heavy.
Check for any leaks in your connections.
Place a bead of gutter sealant along the corner 1 1 2 inches from the edge and hook the front of the corner over the notch.
Old gutters start to display signs of rust and structural weakness.
Rivet the sections together.
Rain gutters take a lot of abuse.
Check again to make sure your piping ends at the right place in your trench.
Next use your garden hose to run water through your gutter system.
Rushing water during rainstorms exposure to weather extremes heavy loads of snow in the coldest climes clogs of fallen leaves and the general ravages of time.
Use your finger to smooth the caulk and push it into the seam to create a water tight seal.
Place the opening of your pvc pipe over the bottom of your spout.
Put the sections together.
Try to do this on the ground if at all possible it s just easier.