Gravel- based drain fields are one of the most common designs used in septic systems.

This design features a bed of gravel with perforated pipes laid on top. The effluent is then dispersed through the gravel and absorbed by the surrounding soil. Gravel- based systems are generally low-maintenance and can be easily repaired if needed. However, they require a considerable amount of space and may not be the best choice for areas with rocky soil.