Either the system is improperly designed or the result of a change in water use habits such as an increase in the size of the family or the addition of a water-using appliance. Surface water draining from roofs, driveways, and roads onto the soil absorption field area can put an extra load on the system. If the soil is saturated with clean water, even seasonally, it cannot accept any more wastewater. The untreated wastewater will either rise to the surface or back up. Physical Damage Driving, paving, or building on top of a soil absorption unit can damage the field.
Pipes can shift or be crushed and the soil compacted.
Damage of this sort can make it difficult to locate the septic tank and prevents access for regular pumping. Tree roots can also clog the soil absorption field. Plant the area in grass, not trees or shrubs. These systems usually fail in a few months because they are inadequately sized, installed in impermeable soils, or not properly constructed. In Oregon, several inches of unsaturated soil must be present beneath the soil absorption system to a limiting layer.