How far above the surface of the ground should the top cover and manhole of a septic tank be extended to prevent surface water infiltration?

To effectively prevent surface water infiltration into a septic tank, it's essential that the top cover and manhole be elevated above the surrounding ground level. The recommended height is typically around 5 centimeters. This elevation allows for proper drainage away from the tank, reducing the risk of rainwater or surface runoff entering the tank and potentially mixing with the effluent.

Maintaining this height is crucial to ensure that the sewage treatment process remains effective. When surface water infiltrates the septic system, it can dilute the wastewater, disrupt the biological processes, and lead to system failure. The 5-centimeter elevation strikes a balance, ensuring that the tank is adequately protected without excessive height that could complicate access for maintenance.

Alternative options might suggest higher elevations; however, raising the top cover and manhole too far above the ground can lead to difficulties in accessing the tank for inspections and maintenance, potentially creating unintended complications for homeowners and service providers. Therefore, the 5-centimeter standard offers an effective and practical solution to managing surface water infiltration while maintaining accessibility.