<human>: Which are the most common types of septic systems?
<bot>: The most common types of septic systems are gravity-based, pressurized, and hybrid systems. Gravity-based systems use a tank that is filled with liquid to separate the solids from the liquids. Pressurized systems use pumps to move the waste through pipes to the septic system. Hybrid systems combine both gravity-based and pressurized systems in order to maximize efficiency.