Once we flush, if not watched, the toilet most of the time fills and fills and overflows, flooding my house. How do we fix this problem? Sorry, let me explain. The toilet does fflush, it's when it is refilling with the clean water. I have had plumbers, rotor rooter, and friends all come out. They ran the something through the air flow up on the roof, they pulled the toilet. Every other drain in the house works fine, including the bathroom in the back of the house. I've plungered, poured all kinds of stuff down the drain, had the septic emptied, don't know what else to try.