Which of the following materials should never be disposed of in a septic system?

The disposal of materials in a septic system is crucial to maintaining its functionality and longevity. Grease and non-biodegradable items should never be disposed of in a septic system because they can cause significant damage to the system. Grease solidifies in the tank and pipes, leading to clogs and reducing the efficiency of the system. Non-biodegradable items, such as plastics, sanitary products, and other similar materials, do not break down and can accumulate, causing blockages that disrupt the flow of waste and may even require costly repairs.

In contrast, biodegradable items, when broken down properly, can be managed by the septic system's natural bacteria. Paper products, while they should be used cautiously, are generally acceptable because they are biodegradable. Food waste can be problematic if disposed of in large quantities, but small amounts can typically break down in the system as well. Therefore, it's essential to avoid putting grease and non-biodegradable materials into a septic system to ensure its proper operation and to prevent costly maintenance issues.