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Problem · Chicago area

Why does my sump pump keep running?

After days of rain or snowmelt, frequent cycling can be normal. Running nonstop in dry weather, or short-cycling every few seconds, usually means something is wrong.

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When it may be normal

In spring thaw and long rainy periods, the water table rises and drain tile can deliver a steady flow — the pump may run often for days. Newer suburban subdivisions with high groundwater commonly see this.

Sump pump system with drain tile and battery backupCross-section: perforated drain tile around the footing collects groundwater and feeds a sump pit. A primary pump and a battery backup pump discharge through a check valve to the exterior, away from the foundation. BASEMENT drain tile at footing discharge away from foundation battery 12345
Diagram How a typical sump system moves groundwater out of a basement. This is groundwater, not sewage — a different system from sewer backflow protection.
  1. Drain tile collects groundwater around the foundation.
  2. Primary pump runs on household power.
  3. Battery backup pump can run during an outage, for a limited time.
  4. Check valve keeps discharged water from falling back into the pit.
  5. Discharge outlet — local rules may say where it can discharge.
Simplified schematic, not to scale. Actual layouts vary by building.

Common causes of problems

Sump pump running or cycling — likely causes
What you noticePossible cause
Runs nonstop, water level not droppingPump worn out or undersized; clogged intake; blocked or frozen discharge
Runs nonstop, pit is emptyFloat switch stuck in the "on" position
Short-cycles every few secondsFailed check valve letting water fall back; float set too tight
Runs in dry weatherWater from another source (a leak, irrigation, or a high water table)
Hums but does not pumpJammed impeller or failing motor

Safe checks

Safety first Do not reach into the pit or handle the pump while it is plugged in. Pit water and electricity are a dangerous mix.
  • From outside, check that the discharge line is not frozen, crushed or buried.
  • Listen for water rushing back into the pit after the pump stops (check valve).
  • Note whether the float can move freely — without touching it while powered.

When to call

  • The pump is running constantly and the water is not going down.
  • Rain is coming and you have no backup pump.
  • The pump is old, noisy or tripping the breaker.

Frequently asked questions

How long should a sump pump run each cycle?

It varies with pit size, pump capacity and inflow. Very short cycles (seconds) or no stop at all are the warning signs.

Can a constantly running pump burn out?

Yes — motors are not designed to run nonstop indefinitely. That is one reason a backup pump matters.

Does it matter where the water discharges?

Yes. Discharge too close to the foundation can recirculate back into the pit; many municipalities prohibit discharge into the sanitary sewer.

Related

Sources

  1. Village of Oak Park — Basement Flooding Prevention Official / primary
  2. City of Elmhurst — Overhead Sewer Program (2023 PDF) Official / primary

Information can change; official sources control.

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