<human>: Which are the most common types of septic systems?
<bot>: The most common type of septic system is a drainfield system. This type of system uses a series of pipes and trenches to collect and treat wastewater. A leach field system is another popular option, which uses a series of trenches filled with gravel or stone that filters out pollutants before allowing the water to seep into the soil. Both drainfields and leach fields require regular maintenance to ensure proper operation.