A high hazard classification includes which of the following?

The classification of high hazard in the context of backflow prevention pertains to any substance that poses a significant risk to public health and safety if backflow occurs. This includes a variety of materials that can contaminate the potable water supply.

Radioactive waste and raw sewage are both critical examples that fall into this high hazard classification due to their potential to cause severe health issues and environmental contamination. Radioactive materials can lead to long-term health complications, while raw sewage can harbor numerous pathogens that can cause widespread illness.

Hazardous chemicals and biological waste also contribute to high hazard classifications as they can be toxic or infectious, posing serious risks when introduced into the drinking water supply.

By including all these categories—hazardous chemicals, biological waste, radioactive waste, and raw sewage—the classification recognizes the broad spectrum of materials that require stringent backflow prevention measures to protect public health and ensure safe drinking water. Thus, selecting the option representing all of the above correctly captures the comprehensive understanding of what constitutes a high hazard.