by Why is my basement floor drain backing up?
Short Answer: A septic blockage or drainage restriction may be preventing wastewater from leaving the property.
Detailed Answer: Floor drains are often the lowest openings in a building. When wastewater cannot move downstream, it commonly emerges through basement drains first. Causes include full tanks, clogged filters, failed pumps, blocked sewer lines, or drain field failure.
Related Questions: What fixture usually backs up first during septic failure? Is basement sewage backup dangerous? How do I tell the difference between a clog and septic failure?