Final answer:
Regular maintenance prevents solids build-up in sewers, minimizing overflows and ensuring sewage treatment processes function effectively to reduce pollution and protect public health.
Step-by-step explanation:
Regular maintenance of sewer systems contributes to their efficiency primarily by preventing the build-up of solids in the sewer. This management practice is important because it minimizes the potential for blockages which can lead to overflows, particularly in combined sewer systems. Overflows can release untreated sewage into the environment, causing water pollution. Regular maintenance also ensures the sewage treatment processes function effectively. Efficient wastewater treatment is crucial for reducing the presence of pathogenic microorganisms, oxygen-demanding waste, nutrients, and toxic heavy metals. By effectively removing solid and organic matter and high levels of harmful bacteria, the treated water is less polluting and sometimes can be reused for irrigation or other non-potable purposes. Furthermore, maintenance supports the secondary treatment process, where aerobic bacteria decompose the organic solids, which is a critical step in the treatment plant.