Towards Environmental Sustainability: Wastewater Management and Sewer Networks for Protecting Groundwater in Rural Settlements

Sewer networks are essential in supporting the sustainable development of rural settlements. However, many municipalities face difficulties due to inadequate or missing sanitation systems. Thus, the contamination of municipal water supplies has become a pressing issue. In the present study, the process of the sewer network establishment and its impacts on groundwater was assessed in the case of a Hungarian settlement. It was found that, following the realization of wastewater agglomeration in 2015, 85% of households in the municipality were connected by 2023. Results indicate that uninsulated septic tanks used before the sewer system resulted in a high rate of sewage leakage. 3D models using RockWorks software show a groundwater dome of more than 1 m in the vicinity of the septic tank. The discharge had a significant impact on groundwater quality; high NH4+ concentrations (>90 mg/L) within the vicinity of the tank and above the limit value (0.5 mg/L) in the total area were detected. Na+ and NO3− concentrations above the contamination limit also reflect the severe impact of wastewater discharge. Significant positive changes in groundwater quality have been detected following sewerage. Our results highlight the importance of similar investments and draw attention to the positive changes that can be achieved. However, a very significant decrease in water levels was detected both in the vicinity of the septic tank and at the municipal level, which, in addition to precipitation patterns, is mainly attributable to the cessation of sewage outflow. Between 2013 and 2022, the average groundwater level declined by 3.8 m in the settlement. Therefore, long-term monitoring of the investment is essential.