Septic System Failure Causes Sewage Backup in House

This case involves a homeowner who bought a house for a family of seven people and experienced two septic system backups before the close of the escrow and two septic system backups after the close of escrow. The purchase contract for the house included an addendum stating that the septic system in the house had been through numerous repairs due to blockage, which the sellers claimed had been a rat colony infestation of the septic tank that had been cleared out by Pest Control. There was a certified clearance on the septic system but there were still plumbing problems that existed. The previous owner of the house agreed to pay for the costs of getting a licensed plumber if the septic system was found to need a new leach field, and possibly a replacement of its PEX pipe system. The house had several other septic backups and during one of the backups, 500 to 700 gallons of sewage spilled from the downstairs toilet and shower into the hall and bedroom. The homeowners had to leave the property because of this backup. An environmental health specialist went to look at the septic system and determined that the septic system had failed.

Question(s) For Expert Witness

1. Could a septic system failure cause sewage to backup from a downstairs toilet into the hallway and bedroom of a house?

Expert Witness Response

A normal septic system is an open system to the environment at its terminal end, the leach field. In cases where the water level is within a few inches from the top of the tank, ground water may enter through cracks in the tank over time and this may cause the tank to be full for many months even after it has been pumped dry. This can occur if there are flooding problems on the property. A sewage backup like this one could also be caused by a block in the septic tank outlet into the leach field. In this case, the large amount of sewage backup indicates that the septic system might have failed. A family of seven people can place an above normal demand on a septic system. If someone places foreign material or excessive toilet paper in the toilet, this could cause a septic backup flow that might continue to spill while water is introduced into the septic system from other sources in the house. In general, if a septic system backup occurs and then a clog is found that is cleared and the system begins working normally again, the system probably has not failed. The clog is usually due to the resident’s misuse of the system. If there is no evidence that a water saturated leach field caused the backup, the backup might have been caused by blockages between the tank and the house.