A civil engineer is required to design a fully functioning and environmentally safe septic system. Not only will they design the septic system, but they will also often oversee the system's installation to ensure what is installed matches what was engineered and approved by the county.

A septic system has two components: a septic tank and a leachfield or drainfield. Primary treatment occurs in the septic tank, where bacteria digest organic materials in the wastewater. The effluent then flows into the leachfield for secondary treatment.