Which of the following materials should never be flushed down a septic system?

Fats, oils, and greases are problematic for septic systems because they do not break down easily and can lead to clogs in the pipes and the septic tank. When these substances are introduced into the system, they can solidify as they cool, creating buildup that can obstruct the flow of wastewater. This buildup disrupts the natural processes of the septic system, impeding the breakdown of waste and possibly leading to system failure or costly repairs.

In contrast, materials like toilet paper, human waste, and biodegradable wipes are specifically designed to break down in a septic system. Toilet paper is formulated to disintegrate quickly in water, making it easy for the system to process. Human waste, being organic, is ideally suited for decomposition by the bacteria in the septic tank. Biodegradable wipes may also break down, but it is important to note that not all wipes labeled as "biodegradable" dissolve as easily as toilet paper, and even some designed for septic systems can cause issues if flushed in large quantities. Therefore, while they are better than fats, oils, and greases, caution is still warranted with their use.

Overall, avoiding the disposal of fats, oils, and greases in a septic system is critical to maintaining its functionality