In such cases we would suggest you to empty your septic tank once every year, although, it can be earlier than the suggested because basically it depends upon your usage and people living in a building, however, it needs to be pumped out occasionally for its smooth operation. Inoperable septic tanks can also cause some problems like sewage backing up into household drains or bubbling up from the ground around the tank. To keep away from health hazards and expensive repairs, we would recommend you to examine and get your tank pumped out for its optimal operation.