Basement Detective

Why Is My Sump Pump Running Constantly After Heavy Rain?

By Basement Detective · Homeowner guidance for Northern Virginia

A sump pump may run frequently during heavy rain because groundwater is refilling the basin quickly. Continuous running, rapid start-stop cycles, or a rising water level can also indicate a float, discharge, or capacity problem. Observe the water level and outdoor discharge from a dry position; have the cause checked before replacing the pump.

A pump that is moving water may still leave the basement wet if water is entering somewhere the drainage system does not collect it. Do not touch electrical parts, reach into the basin, remove a sealed cover, or take the pump apart to investigate.

For homes in Alexandria, Arlington, Fairfax County, and nearby Northern Virginia, the first step is to distinguish frequent operation during a storm from a pump that cannot shut off or keep up. The fix depends on which condition you have.

What does “running constantly” mean?

What you observe	What it may mean	Next step
The pump runs for a while, stops, then starts again as the basin refills during rain	The system is removing incoming water; the amount of inflow and discharge path still matter	Watch whether the basin level falls each cycle and whether water is leaving the outlet
The motor keeps running even after the basin appears low	The float may be obstructed, misadjusted, or faulty	Arrange pump service; avoid handling the switch around standing water
The pump starts and stops every few seconds	This is short cycling; water may be returning through the discharge line, or the basin/switch range may be unsuitable	Have the check valve and float operation evaluated
The motor runs but the basin level does not fall, or water appears in the basement	The outlet may be blocked, the pump may not be moving enough water, or the leak may bypass the sump system	Seek prompt inspection, especially if the water level is rising

Pump manufacturer Zoeller describes rapid start-stop behavior as short cycling and lists check-valve and switch-range issues among possible causes. Its residential sump-pump service checklist (July 2026, page 2) separately lists an obstructed float, discharge blockage, and pump capacity limits for pumps that do not shut off or move enough water. Those are possible causes, not a diagnosis of your installation; service must follow your model's instructions.

Five checks you can make without taking the pump apart

Observe the basin water level only if it is already visible from a dry, safe position. Does it fall while the pump runs, remain steady, or continue to rise? Do not remove a sealed cover. If water is approaching electrical equipment or you would need to stand in water to inspect it, leave the area and call for help.
Look for water leaving the outdoor discharge outlet. A running motor with little visible outflow may indicate a restriction or pump problem. Do not disconnect piping or reach into the basin while the pump is powered.
See where the discharged water goes. Water sent back toward the foundation can return to the drainage system. The Northern Virginia Soil and Water Conservation District advises directing sump discharge away from the house and avoiding outlets that create problems for neighbors.
Notice whether the pump stops after rain eases. Record when it starts, how long it runs, and whether the basin refills rapidly. A short video of the basin and outlet can help a technician distinguish continuous running from rapid cycling.
Check for other rainwater paths. Overflowing gutters, downspouts emptying near the foundation, poor grading, and blocked stairwell drains can add water near the basement. The Fairfax County drainage guide lists these as common checks for wet basements.

When should you call for an assessment?

Request help promptly if the water level rises while the pump runs, the motor will not stop after the basin empties, the discharge outlet has little or no flow, or water is entering finished space. If the pump keeps working but the basement is still wet, the water may be entering through a wall-floor joint, crack, window well, or another path that needs its own diagnosis.

A useful assessment checks the basin and float, pump output, check valve, discharge route, and where water reaches the basement. It should also examine gutters, grading, and the drainage path feeding the basin before assuming that a larger or replacement pump is the answer. Fairfax County's homeowner drainage guidance notes that a working sump can coexist with water emerging at the floor joint if the under-floor drain does not collect or move that water properly.

Frequently asked questions

Is it normal for a sump pump to run frequently during heavy rain?

It can be. Groundwater may refill the basin quickly during a storm. The important observations are whether the basin level falls, the pump turns off between cycles, water exits the discharge, and the basement stays dry. Running without lowering the water level needs attention.

Why does my sump pump keep turning on and off every few seconds?

That pattern is called short cycling. A check valve that lets water return, a small basin, or a narrow switch range are possible causes. Zoeller's support guidance explains that short cycling can shorten switch life. Have the system checked instead of repeatedly changing the float without understanding the installation.

Can a sump pump run constantly and still leave the basement wet?

Yes. It may not be moving water fast enough, its discharge may be restricted, or the water may be entering beyond the area served by the sump drainage. The leak location and flow path determine the repair.

Should I replace the pump immediately?

Not on the running pattern alone. A failed pump may need replacement, but a blocked outlet, float issue, recirculating discharge, or drainage problem can produce similar symptoms. Diagnose the pump and water path first.

Get help with a sump pump that is not keeping up

Basement Detective assesses wet basements and sump pump problems in Northern Virginia. If the basin is filling, the pump will not shut off, or water is still entering the basement, request a sump pump assessment or call (703) 684-0860. We look at the pump and the route water takes into and away from the home.