A local health department can't approve a septic system with a daily sewage flow of over ______ gallons per day.

• A. 1,000
• B. 2,000
• C. 3,000
• D. 4,000

Answer: (B)

In septic system design, the daily sewage flow is used to determine the size of the treatment and absorption components. Health departments cap the design flow for conventional systems to ensure the system can reliably treat and dispose of the effluent in the soil. When the expected daily flow goes beyond that cap, a standard system can’t be approved and an alternative wastewater solution is required.

The commonly used threshold in many codes is 2,000 gallons per day. So flows over 2,000 gpd exceed what a standard septic system is approved to handle, necessitating a different approach such as a larger or alternative system or connection to municipal sewer.