During inspections, internal floor drains are checked to ensure they are not connected to which of the following?

The correct answer is that internal floor drains must not be connected to storm sewers or surface waters. This is crucial for environmental protection and regulatory compliance. Internal floor drains are typically part of an industrial facility's wastewater management system. If these drains are connected to storm sewers, any polluted water from the facility could inadvertently enter natural water bodies during rain events, leading to contamination of surface waters and violation of water quality standards.

Stormwater regulations are designed to prevent pollution from industrial activities that may discharge harmful substances to storm drains. By ensuring that internal floor drains are not linked to storm sewers, facilities can effectively manage and treat wastewater separately, reducing potential harm to the environment.

The other options include systems that have specific purposes and regulations, but they do not have the same direct implications for stormwater contamination. For instance, domestic water systems and sewage treatment plants serve different functions and have their own regulatory frameworks. Likewise, industrial waste systems are typically designed to handle specific types of wastewater, but the focus here is on protecting stormwater and surface waters from pollution, making the connection to storm sewers particularly critical in inspection protocols.