Which type of sewage system may be used if the soil is unsuitable for a conventional septic system?

An alternative treatment system is the correct choice for situations where the soil is unsuitable for a conventional septic system. These systems are designed specifically to handle waste in areas where traditional systems may fail due to poor drainage or soil conditions that do not allow for adequate filtration or absorption of effluent.

Alternative treatment systems can include technologies such as sand filters, aerobic treatment units, or constructed wetlands, which provide additional processing of sewage and create a more suitable environment for treatment. This adaptability is crucial for ensuring proper waste management and environmental protection, particularly in areas with high water tables or clayey soils that do not adequately filter wastewater.

While a surface drainage system may manage stormwater or surface runoff, it does not treat sewage. A gravity-fed system relies on the natural flow of wastewater, but if the soil is unsuitable, gravity systems will not function as intended. A direct discharge connection, on the other hand, is typically not used for sewage disposal unless specifically permitted and is more common in urban or industrial settings with treatment facilities. Therefore, the alternative treatment system is the most appropriate solution in this scenario.