Which types of soils are most suitable for subsurface absorption of wastewater?

The most suitable types of soils for subsurface absorption of wastewater are red, yellow, and brown soils. These types of soils generally possess good drainage characteristics and a favorable structure that allows for efficient absorption and filtration of wastewater. They often have adequate permeability to facilitate the movement of water while also filtering out contaminants effectively as the wastewater percolates through the soil layers. This capability is critical for ensuring that pollutants are adequately treated before reaching groundwater supplies.

Clay soils, while they may retain water well, are not ideal for absorption systems due to their low permeability, which can lead to ponding and inadequate wastewater treatment. Sandy soils, although they have high permeability and good drainage, may lack the necessary nutrient and microbial content to effectively treat wastewater, leading to potential pollution issues. Mottled soils can indicate poor drainage and high water tables, complicating their effectiveness for subsurface absorption systems. Therefore, red, yellow, and brown soils offer the best combination of properties for wastewater absorption applications.