Drain field repair and replacement
When wastewater surfaces in the yard or drains stop keeping up, the drain field is often the reason. Get it diagnosed before you replace it.
The drain field, sometimes called a leach field or drainfield, is where the soil finishes treating wastewater from the tank. It's usually the most expensive part of a septic system to replace, so the first step is always a diagnosis. Sometimes the field itself is fine and the real problem is a clogged line, a failed pump, or a tank that's letting solids through.
Signs of a failing drain field
- Soggy ground or standing water over the field
- Sewage odor in the yard, especially after heavy water use
- Grass that's unusually green and lush over the lines
- Drains that back up even after the tank was pumped
- An inspection report noting ponding in the field
Why drain fields fail around Olympia
Western Washington's wet winters raise groundwater levels, and a field that barely keeps up in summer can be overwhelmed in January. Soils vary a lot across Thurston County, from gravelly prairie ground to heavier soils that drain slowly. Beyond weather and soil, the usual causes are:
- Solids escaping a tank that wasn't pumped often enough, or has a broken baffle
- Driving or parking on the field, which compacts the soil and crushes pipes
- Roots from nearby trees and shrubs working into the lines
- More water than the system was designed for, such as an added bedroom or leaking fixtures
- Old age: every drain field has a working life
Repair or replace?
Some fields can be rehabilitated by fixing the cause and giving the soil time to recover. Others need new lines, or a different system type such as pressure distribution or a mound when the site conditions call for it. Replacements in Thurston County require permits and a design that fits your soil and lot, so work with professionals who handle this regularly.
Where we connect you with help
Common questions
Can a failing drain field recover?
Sometimes. If the cause was excess water or solids from an overdue tank, fixing that and resting the field can help. A saturated or clogged field in poor soil usually needs repair or replacement.
Do I need a permit to replace a drain field?
Yes. Drain field replacements in Thurston County require permits and a design. Your septic professional or designer handles this.
Other septic services
Septic backing up or alarm going off?
Call now instead of sending a form. Backups are a same-day problem.