Which materials should be avoided in a septic system?

The correct choice highlights materials that can significantly disrupt the biological processes and effectiveness of a septic system. Grease, oils, and chemicals can lead to clogging, reduce the microbial activity necessary for breaking down waste, and ultimately result in system failure.

Grease and oils can layer on top of the wastewater, preventing proper treatment and filtration. When these substances accumulate in the tank or leach field, they can block pipes and reduce the space available for wastewater to flow, leading to backups and overflows. Furthermore, harsh chemicals can kill the beneficial bacteria that are essential for digesting waste, further compounding issues within the septic system.

In contrast, food scraps and biodegradable waste, while they should still be minimized, break down relatively well in the system. Toilet paper and human waste are the primary inputs that septic systems are designed to handle. Rainwater and greywater can be managed in certain ways depending on local regulations, but they are typically not considered harmful to the septic system as long as they enter the system in controlled amounts. Thus, avoiding the inclusion of grease, oils, and chemicals is crucial for maintaining both the functionality and longevity of a septic system.