Where must an adequate supply of both hot and cold running water be available?

An adequate supply of both hot and cold running water must be available on the facility premises and in any work area with hazardous materials. This requirement is crucial for maintaining hygiene and safety standards, particularly in areas where chemicals or potentially harmful substances are used. Access to running water allows for proper sanitation, which is vital when handling products that may pose health risks.

In work areas with hazardous materials, having running water available ensures that any spills or exposure can be addressed immediately, minimizing potential harm to clients and staff. It also plays an essential role in the overall cleanliness of the workspace, helping to prevent contamination and ensuring compliance with health regulations.

Availability in employee break rooms, administrative offices, or just restroom facilities does not meet the necessary guidelines for overall safety in all operational areas of a cosmetology facility. Therefore, the correct answer emphasizes the importance of accessible water in all work areas, particularly those involving hazardous substances.