When is it permissible to connect a storm drain to a sanitary sewer?

Connecting a storm drain to a sanitary sewer is generally considered permissible when the drained area is not greater than 50 square feet. This is typically based on regulatory guidelines aimed at preventing overloading the sanitary sewer systems with excess stormwater, which can lead to backups and potential health hazards.

The logic behind this regulation is that small areas of drainage, such as those that are only 50 square feet or less, likely won't contribute a significant volume of stormwater to the sanitary sewer system. Thus, it is manageable and does not pose a substantial risk of overwhelming the system, especially in heavy rainfall situations.

In contrast, larger areas or different circumstances can result in significant stormwater runoff that the sanitary sewer is not designed to handle, leading to various issues such as sewer spills or system failures. Therefore, the specific size limitation ensures compliance with health and safety standards while managing stormwater effectively.