What is the Difference Between Sewer vs. Septic?

Photograph of a large side yard of a brown ranch home in Florida. A purple Dodge Ram truck with a decal that says "ACE Septic & Waste" sits in the back. Large areas have been dug out, and two works are setting up septic system components.

Ultimately, both sewer and septic systems properly dispose of wastewater. The main difference is that septic systems operate independently, while sewers are connected to the main sewer supply and treated in large plants.