This thread brings back baaad memories.
When we first moved into this house, we had never lived with a septic tank before.
About three months after we moved in, the gurgling started. Then came the water backing up into the bathtub. We thought it was odd, but didn't have a clue what it meant. About the time I realized that running the washing machine made it worse... I ran the washing machine before work and came back to a completely flooded bathroom, bedroom, and half the living room. It smelled so awful. Gag. Bad memories. I know better now and I freak out every time I hear the "gurgle", which usually means the GFI at the pump tripped.