Final answer:
Indoor trash cans according to the food code need to be leak-proof to maintain hygiene and prevent potential contamination from liquid waste.
Step-by-step explanation:
According to the food code, indoor trash cans must be leak-proof. This requirement is crucial to maintain hygiene and prevent liquid waste from seeping out, which could lead to contamination and attract pests. While the question touches upon aspects of waste management, including biodegradable waste, recyclable materials, and inert waste, the most relevant information provided for this question is the necessity of a trash can being leak-proof within a food-related environment for health and safety measures.