Proper waste-water disposal is essential for preventing cross-contamination and environmental hazards. According to the ServSafe Manager curriculum and the FDA Food Code, all "grey water" or dirty water resulting from floor cleaning must be disposed of in aservice sink(also known as a mop sink or utility sink). These sinks are specifically designed with deep basins and often have a floor-level drain or a high-back splash guard to prevent the spray of contaminated water onto surrounding surfaces.

Disposing of mop water in a toilet (Option A) is unhygienic and can lead to splashing on surfaces that people touch. Dumping water outside (Option C) is often illegal under local environmental codes and can attract pests to the exterior of the building. Using a three-compartment sink (Option D), which is reserved for cleaning and sanitizing food-contact equipment, is a major health code violation that directly causes cross-contamination. Mop water is filled with dirt, grease, and potentially harmful microorganisms likeListeriathat thrive on floors. By using a dedicated service sink, the operation ensures that these contaminants are kept entirely separate from food-prep and warewashing areas. Additionally, the service sink should be equipped with a backflow prevention device (such as an air gap or vacuum breaker) to protect the facility's clean water supply from being contaminated by the dirty water in the sink.