What is an additional criterion for sewage systems to be deemed unsafe?

Sewage systems can be considered unsafe if they are not maintained according to regulations. This criterion is crucial because proper maintenance is essential for ensuring that sewage systems operate effectively and do not pose health or environmental risks. If a system is not maintained according to established standards—such as regular inspections, cleaning, and repairs—it can lead to malfunctions that could result in contamination of water supplies, public health hazards, and violation of local health codes. Essentially, adherence to maintenance regulations ensures the sewage system is kept in a safe state, thereby protecting both the environment and public health.