Sump Pump Running Constantly: Causes & Fixes
Quick answer A sump pump running constantly is usually caused by a stuck or misadjusted float switch, a failed check valve, or a pit that is simply too small for the water volume. Identify the cause below and follow the steps to fix it.
Quick-Diagnosis Table
| Symptom | Most Likely Cause | DIY Difficulty |
|---|---|---|
| Pump runs but pit stays full | Worn impeller or undersized pump | Moderate |
| Pump runs, pit empties quickly, then refills fast | Failed check valve or high water table | Easy–Moderate |
| Float visibly stuck against wall or pump body | Mispositioned or tangled float switch | Easy |
| Pump runs only during or after heavy rain | Undersized pit or pump capacity | Hard (excavation) |
| Pump runs 24/7 regardless of weather | Groundwater intrusion or cracked liner | Hard |
| Pump hums but water level doesn’t drop | Clogged or failed impeller | Moderate |