What distinguishes a large onsite wastewater system?

The defining characteristic of a large onsite wastewater system is its capacity to treat more than 1,500 gallons of wastewater per day. This threshold is significant in regulatory contexts, impacting the design and operational standards that must be adhered to in order to manage wastewater effectively and safely. By exceeding this volume, such systems typically require more advanced treatment technologies, monitoring, and maintenance, reflecting their higher potential impact on the environment.

In contrast, systems serving single-family homes typically manage smaller volumes that are less complex in requirements. While professional installation may be recommended for all systems, it is not a distinguishing factor since both large and small systems can be installed by licensed professionals. Discharging directly into public waters is related to specific discharge permits and regulations, but it does not define a large onsite wastewater system; rather, it addresses the final effluent management option, which could apply to different system sizes. Thus, the volume threshold of 1,500 gallons per day is the critical element that determines whether a system is classified as large.