Lawn Patches Over Septic Drain Field: Soil Depth or Saturation?

Two Likely Causes for Drain Field Lawn Issues

A Western Washington homeowner had shorter, yellower grass over a new septic drain field (planted late March). Farm soil used, no imported topsoil.

Diagnosis Options

Expert Lean: Drought Stress

"Good news: your drainage ditch works as supposed to." Farm soil usually good quality. Adding topsoil increases water-holding capacity over drain lines.

Repair Method

1. Cut existing sod in 1x1 ft squares with 1 inch soil.
2. Set aside, keep moist.
3. Add quality topsoil to achieve 6-8 inch depth.
4. Replace sod squares. Water daily 2 weeks until re-rooted.
5. If grass poor, remove and reseed instead.

Why Not Import Topsoil Initially?

Farm soil often superior to bagged topsoil. But depth matters—drain fields need adequate cover for both effluent treatment and grass health.