An auxiliary tank shall be provided with an overflow pipe that drains where?

The requirement for an auxiliary tank to have an overflow pipe draining to the top of the supply tank is rooted in safety and operational efficiency. By directing overflow back into the supply tank, it ensures that any excess fuel is not wasted and remains within the system, preventing environmental contamination or issues associated with fuel spillage. This approach minimizes the risk of hazardous situations that could arise from overflow and maintains the integrity of the storage system.

The design serves multiple purposes: it helps avoid the potential for overfilling an auxiliary tank, ensures that fuel does not escape the confines of the intended storage, and can assist in maintaining the desired operating levels of the supply tank. In contrast, other options like draining beneath the building or out of the property line would pose significant risks, including environmental hazards, legal liabilities, or damage to surrounding areas, while draining into a drainage system could lead to pollution or contamination concerns.