Most sewer backups happen because the line is plugged with an obstruction. However, backups can be caused by several factors including the condition of the sanitary sewer system itself, natural phenomena such as earth movement, heavy rainfall, and the incorrect usage of the system by the public.
Some common backup causes are:
- Solids / debris – Typical solids that buildup in the pipe and cause backups are dirt, hair, bones, tampons, paper towels, kitty litter, diapers, broken dishware, garbage, concrete, and debris.
- Fat/Oil/Grease - When fat, oil or grease is discharged into a sewer system they will solidify and, after a while, can build up and plug drain lines in your building or complex. They can also plug the sewer lines owned by the District, thus increasing the maintenance cost to the District. Plugged sewers can also cause flooding of nearby private homes and businesses.
- Tree Root infiltration – Tree roots can cause backups. Roots can infiltrate the pipe system and block the wastewater flow.
- Water inflow/infiltration – Rainwater entering the public sewer line can cause system problems and overflows. If the sanitary sewers only transported wastewater, backups would only occur when obstructions were present in sewer pipes. However, during certain wet weather conditions, sanitary sewers can become overloaded with groundwater or storm water runoff so they become surcharged or overloaded. This results in backups into lower levels and basements, or slow running services.
- Structural defects in pipes and manholes – Significant sags, bellies in the line, cracks, holes, protruding laterals, misaligned pipe, offset and open joints and collapsing pipe material are all possible causes of backups.