A drainfield fails gradually and then suddenly. The early signs are easy to ignore and the late ones are expensive, so it is worth knowing which is which.
This is one chapter of our complete guide to owning a septic system.
The early signs
Drains across the house slow down at the same time. One slow drain is a clog; every drain is a system.
Grass over the field grows greener and faster than the rest of the yard, because it is being fertilised by effluent that should be moving down instead of up.
The signs that mean stop
Standing water or soft ground over the field, especially in dry weather. Sewage odour outdoors near the field, or indoors at floor drains.
Backups at the lowest fixture in the house. At this point every gallon you send down makes it worse — stop laundry and dishwashing and call.
What actually caused it
The most common cause by a wide margin is a tank that went too long between pumpings, letting solids carry over and seal the soil. See pumping frequency.
Others: hydraulic overload from a leaking fixture, compaction from vehicles parked over the field, root intrusion, and a system reaching the end of a thirty-year life.
Need a hand with this?
Send your address and we will route you to the Bur Oak company that covers it.
Common questions
Can a failed drainfield be repaired?
Sometimes. Jetting laterals, replacing a distribution box, or resting the field can buy years. A field sealed by solids usually needs replacement.
How much does replacement cost?
In the Midwest, typically $10,000–$30,000 depending on soil, size and access.
Keep reading
- How often to pump
The maintenance that prevents this.
- Inspections
What an inspector looks for.
- Costs
What each repair actually runs.