Guide
Slow drains, wet spots, odours and gurgling — what each septic symptom points to and how urgent it is.
| Symptom | Likely cause | Urgency |
|---|---|---|
| Every drain slow at once | Tank full, or blockage between house and tank | Days |
| One fixture slow | Local clog, not the system | Low |
| Gurgling drains | Restricted flow or a blocked vent | Weeks |
| Soggy ground over the field | Field saturated or failing | Immediate |
| Unusually green strip over the trenches | Effluent surfacing near grade | Immediate |
| Sewage odour outdoors | Surfacing effluent, or a broken lid | Immediate |
| Sewage odour indoors | Dry trap or vent issue, usually not the tank | Low |
| Backup after heavy rain only | Groundwater flooding the field | Weeks |
Before anyone quotes you for a new field, check three things: whether the tank is simply due for pumping, whether the effluent filter is clogged, and whether the distribution box has settled and is sending everything to one trench. Any of the three can produce symptoms that look exactly like field failure, and all three are inexpensive to fix.
Effluent surfacing, persistent saturation, and backups that continue after a pump-out point to a field that has lost its ability to accept water. Sometimes the trench bottoms are sealed by solids from years of skipped pumping; sometimes the field was undersized from the start; sometimes it is simply thirty years old.
Resting a field by drastically reducing water use for several weeks occasionally helps a marginal case. More often the answer is a new field, in the reserve area that should have been kept clear.
Surfacing sewage is a health hazard, not an inconvenience, and continuing to load a failing field makes the eventual repair larger. Call a licensed inspector, and call your health department if effluent is reaching the surface or a watercourse.