Non-food contact equipment must be all except:

Non-food contact equipment is crucial in maintaining food safety and hygiene standards in a food service environment. The requirement for such equipment to be smooth, waterproof, and corrosion resistant is tied to their ability to be cleaned easily and maintain durability over time, preventing any contamination risks that could arise from surface imperfections, moisture retention, or rust.

Smooth surfaces are essential because they prevent food particles and bacteria from adhering to them, making cleaning easier and more effective. Waterproof materials are important as they help in preventing water damage and do not allow for moisture retention that could facilitate the growth of harmful microorganisms. Additionally, corrosion-resistant materials ensure that the equipment can withstand exposure to water and cleaning chemicals without deteriorating, which could lead to contamination.

While all these factors are critical for ensuring that non-food contact surfaces operate effectively in a food environment, "tempered" does not apply as a necessary characteristic for non-food contact equipment. Tempering generally refers to a heat treatment process used to increase the toughness of material, particularly in glass and metals, and is not a relevant requirement for non-food contact equipment in terms of functionality or sanitation.

Thus, the lack of necessity for non-food contact equipment to be tempered makes this the correct choice, highlighting the importance of focusing on smoothness,