How To Fix A Blocked Outside Drain [upd] -

If you have large trees near your drainage line, roots will seek the moisture. If you find roots in your drain, do not just chop them; consider hiring a professional to "root cut" or, better yet, replace the section of pipe with a root-proof alternative.

Ensure your drain cover is in good repair. If it has holes large enough for a golf ball or heavy mulch to pass through, replace it with a fine mesh cover. This is your first line of defense. how to fix a blocked outside drain