Neighbor ...person who has ground next to us ran quite a bit of tile in some draws and down thru a waterway that exits onto us.  He had the tile guy ask about hooking it into our 6" main.  Husband said no, can't dump a 10" into a 6" with out doing damage; tile guys agreed, but fella next door had the guys do it anyway.   Tile guys got to dig it back up and undo it.....and bill the other person for the time.....it dumps on our grass waterway now, but at least it doesn't blow out our 6" every time we (used to) have a big rain.