We live in Vancouver, Washington, where it rains most of the winter. Our downspouts go down the side of the house and disappear into a hole in the ground. However, there is a clog at some point underground. I don't know if they eventually connect up to sewer or storm sewer.
The house was built 27 years ago. We bought it 4 years ago, but gutters were already clogged. We have 4 very large Douglas fir trees along the back of the house that provide plenty of stuff to clog the gutters all year long. I clean the gutters 2 to 3 times a year, and in the first year we owned the house I added wire mesh thingies over the places where the downspouts connect to the gutters. That keeps more stuff from going down, but that is like closing the barn door after the horses got out.
What is the best way to solve the problem? Is it renting a rotor-rooter type machine? Is it giving up on the undergound system and diverting the water on the surface? A previous owner put a lot of large concrete areas around the house, so water doesn't get into the crawl space.