Exterior sump on a simplex system must have a minimum holding capacity above the high level alarm of at least how many days?

• A. 0 days
• B. 1 day
• C. 2 days
• D. 3 days

Answer: (B)

The main idea is to provide a buffer in the exterior sump so the system has time to respond if the high level alarm trips. For a simplex system, the exterior sump must hold at least a day’s worth of wastewater above the high level alarm. This extra capacity acts as a safety margin during pump outages or service delays, preventing immediate overflows and giving you time to restore operation or address the issue. Zero days offers no backup, and while more than one day provides more buffer, the minimum required by the standard is one day.