What is a significant environmental benefit of effective sewage disposal systems?

The significant environmental benefit of effective sewage disposal systems is that they minimize risks of contamination to water sources. Proper sewage disposal is crucial for protecting surface water and groundwater from pollutants, pathogens, and other harmful substances found in human waste and wastewater. When sewage is treated effectively, it prevents these contaminants from entering natural bodies of water, which can preserve aquatic ecosystems, maintain water quality for public health, and safeguard drinking water supplies. This function is vital in reducing the incidence of waterborne diseases and protecting both human and environmental health.

Considering the other options, eliminating all waste products is not feasible; sewage systems can significantly reduce but not entirely remove all waste. While effective systems can lead to reduced costs for municipalities over time, cost efficiency is not primarily their environmental focus. Providing recreational areas can be a secondary benefit, but it does not directly relate to the core environmental impact of sewage disposal systems. Therefore, minimizing risks of contamination is the most direct and essential environmental advantage.