Drain Field Repair Services

The drain field (also known as a leach field or absorption field) is the part of your septic system where treated wastewater percolates into the soil for final treatment and disposal. When a drain field fails, it is often the most expensive component to repair or replace, making early detection and proper maintenance critical.

Drain field failure typically manifests as standing water or soggy ground over the field area, sewage odors in the yard, unusually green or lush grass over the drain field compared to surrounding areas, slow drains throughout the house, or sewage backing up into the lowest drains. These symptoms indicate that the soil can no longer absorb effluent at the rate it is being delivered.

The most common cause of drain field failure is biomat accumulation. Biomat is a biological crust that forms naturally at the soil interface where effluent meets the native earth. In a healthy system, biomat stays thin enough to allow water to pass through. But when a system receives too much water, too many solids (from a tank that wasn't pumped often enough), or harmful chemicals, the biomat grows thick enough to seal the soil and prevent absorption.

Repair options depend on the severity of the failure. For minor issues, resting the drain field by reducing water usage and pumping the tank may allow the biomat to break down naturally. Chemical or biological treatments can be introduced to accelerate biomat decomposition, costing $500 to $2,000. For more severe failures, techniques like terralift (pneumatic fracturing of the soil) can restore permeability at a cost of $1,500 to $5,000.

When repair isn't viable, partial or full drain field replacement is necessary. This involves excavating the failed area, removing the old gravel and pipe, and installing new absorption trenches. Replacement costs range from $5,000 to $20,000 or more depending on the size of the system and local soil conditions. In some cases, a completely new drain field must be installed in a different area of the property, which requires a new perc test and permit.