Last night I did a load of laundry and one of my toilets overflowed. I cleaned it up and didnt think any more about it. Later on we took showers and once again the toilet overflowed. I should mention that we have 2 bathrooms one on main floor and 1 in basement, the one in the basement is the one that is overflowing. We turned off the water to the toilet and drained it, bowl and tank. We discovered that every drain in our house goes right into that toilet. I do have a septic tank but i also have 3 children so something could have gotten flushed! If anyone could help me out i would appreciate it. thanks