Waste water backups can result from issues with any of the three major system components.

Drain/Vent: Clogs may occur - follow the recommendations of the Septic Use page to help avoid clogs. Special note for toilets. Clearing clogs can be done by any of the typical methods: chemical (drain cleaners), mechanical (snakes/routers), or pneumatic (compressed air).

Septic Tank: The fluid entry/exit of the tank can become clogged if the amount of solid waste in either the scum or sludge layers within the tank becomes excessive. To prevent this, follow the recommendations of the Septic Use page, and be sure to pump out the septic tank at the recommended intervals. Typically, a pumping and cleaning of the septic tank will solve any septic tank clogging related problem. The septic tank is usually located near the surface of the ground, and may become damaged. Avoid having significant weight placed above the tank (e.g. do not park vehicles over the tank, do not allow livestock to roam over the tank, etc.). Finally, tree and shrub roots can damage pipes and the tank. Avoid planting large plants near wastewater lines and the septic tank.

Leach Field: Piping in the leach field can be clogged, or the leach field itself can become filled with solid waste particles. These are expensive failure modes as they will typically require replacement of part or all of the leach field. To avoid this condition, be sure to follow the recommendations of the Septic Use page, and be sure to pump out the septic tank at the recommended intervals. The leach field may also loose its ability to absorb water due to other external drainage conditions (excessive rainfall, down spouts or ditches that drain over the leach field, etc.). Try to avoid drainage of surface water over leach fields. The leach field will usually recover when the excess water drains away. The leach field may be damaged or experience a reduction in absorption capacity due to soil compaction if significant weight is placed above the field (e.g. do not park vehicles over the field, do not allow livestock to roam over the field, etc.). Finally, tree and shrub roots can damage pipes and the leach field. Avoid planting large plants near wastewater lines and the leach field.

If the waste water system normally works fine, but backs up only when having a party or having visitors, this can be a sign that the septic tank needs to be pumped, but may also indicate that the system is undersized for its use or that the leach field is failing.


For more details about septic systems, see the Inspectapedia website.