Is Using a Garbage Disposal Bad for a Septic Tank?

Organic Matter

• Food placed in a garbage disposal, even though it is ground up, does not break down right away and ends up in the septic tank. This increases the amount of organic matter inside the tank. Frequent use of a disposal can increase the organic matter by as much as 50 percent, or be the equivalent of another person living in the household. This puts a strain on the system to process a large amount of organic matter.

Balance

• A septic tank depends on a balance of different types of materials in order to break down organic matter and properly function. Since a garbage disposal adds a large amount of organic matter to the system, the matter may disrupt the balance. There may not be enough beneficial bacteria to break down all the waste, and the ratio of waste water to solid matter also could become out of balance, slowing down the decomposition process and creating odors.

Cleaning

• Large amounts of organic matter deposited into a septic system from a garbage disposal increases the number of necessary cleanings. If a disposal is used regularly, the septic tank needs to be cleaned at least once a year, instead of every two to five years under normal circumstances. This is because the organic matter cannot break down as fast as it is deposited into the tank, resulting in build-up.

Blockage

• Food particles deposited into a septic tank system through a garbage disposal often are small enough to make their way through to the drain field or leach field, but are large enough to block the soil drainage system. A blockage in the leach field can cause the septic tank to back up or the leach field to flood.