Sump Pump Keeps Running: 7 Causes (Float Switch, Check Valve, Discharge) + Fixes

If your sump pump keeps running, don’t ignore it. Continuous running can burn out the motor, drain your backup battery, and still leave you with a wet basement. However, the cause is often straightforward once you know what to check: a stuck float, a failed check valve, a blocked discharge, or heavy inflow that the pump can’t keep up with.

This guide is written for Maryland basements in Gaithersburg (20878) and nearby Montgomery County areas including Rockville, Germantown, North Potomac, Darnestown, Montgomery Village, Potomac (north), Derwood, Kentlands, and Washington Grove.

Sump pump keeps running: safety first

Before you troubleshoot, keep it safe:

• If water is near outlets, cords, or panels, turn off the breaker before touching anything.
• If the water looks dirty or smells like sewage, stop and treat it as a sewer issue. In that case, start with Video Camera Sewer Inspection.

Also, remember: a sump pump is designed for groundwater. In contrast, a sewer backup needs a different diagnosis.

Sump pump keeps running: quick diagnosis in 60 seconds

First, answer these three questions:

1. Is the sump pit water level dropping while the pump runs?

• If yes, you may have heavy inflow or a high water table event.
• If no, you likely have a discharge blockage, failed check valve, or pump problem.

2. Is water coming back into the pit immediately after shutoff?

• If yes, the check valve may be failing or installed incorrectly.

3. Did this start suddenly after a storm or freeze?

• If yes, suspect discharge line issues (blockage or freezing), or an inflow surge.

Next, use the cause list below to confirm the exact issue.

Sump pump keeps running: 7 common causes (and what to do)

1) Sump pump keeps running because the float switch is stuck

Float switches fail more than pumps do. Therefore, start here.

What you’ll notice

• Pump runs even when the pit is low
• Float looks pinned to the pit wall or tangled in cords

Safe fix

• Turn off power.
• Free the float and secure cords so nothing interferes.
• Then, test again.

2) Sump pump keeps running because the float is set too high or too sensitive

Sometimes the float activates too early or never reaches the “off” point.

What you’ll notice

• Pump runs longer than normal
• Cycling behavior looks abnormal

Safe fix

• Adjust the float range if your design allows it.
• If not, replace the switch with a better design.

3) Sump pump keeps running because the discharge line is frozen or blocked

A blocked line lets the pump run without lowering the pit.

What you’ll notice

• Pump hums or runs, but water level doesn’t drop
• You see little or no water exiting outside

Safe fix

• Check the exterior discharge point.
• Look for ice at the outlet or a crushed/kinked hose.
• If freezing is common, reroute or shorten exterior runs and ensure the line drains down.

4) Sump pump keeps running because the check valve failed (or is backwards)

A failed check valve allows backflow. As a result, the pump runs more often and longer.

What you’ll notice

• Water falls back into the pit after shutoff
• You hear a loud “thunk”
• The pump seems to “fight” the same water repeatedly

Safe fix

• Confirm the arrow on the check valve points away from the pump.
• Replace a cheap or sticking valve with a quality model.
• Add a union for service access if needed.

For an inspection perspective on sump components and failure modes, InterNACHI has a helpful guide: https://www.nachi.org/sump-pumps.htm

5) Sump pump keeps running because the pump is undersized (high inflow event)

Sometimes the pump runs continuously because the water table is high and the pump can’t catch up.

What you’ll notice

• Pit level drops slowly or barely
• Heavy rain correlates strongly with the problem
• The pump runs hard but water still rises

Safe fix

• Upgrade to a higher-capacity pump or add a secondary pump.
• Add a battery backup sump pump system if outages happen during storms.

6) Sump pump keeps running because the impeller is jammed or the intake is clogged

Debris can reduce pumping capacity. Therefore, the pump runs longer to move the same water.

What you’ll notice

• Weak discharge flow
• Gravel, sludge, or debris in the pit
• Strange noises from the pump body

Safe fix

• Turn off power.
• Clean the pit and remove debris safely.
• Consider a sealed lid to reduce future debris.

7) Sump pump keeps running because water is returning toward the foundation

Sometimes the pump works, but grading or discharge placement sends water right back. Consequently, the pit refills and the pump never gets a break.

What you’ll notice

• Discharge exits too close to the foundation
• Soil stays saturated near the wall
• Pump runs often even after light rain

Safe fix

• Extend the discharge away from the house.
• Improve slope away from the foundation.
• Avoid dumping onto sidewalks that drain back toward the home.

Sump pump keeps running: when to call a plumber

Call a pro if:

• The water level does not drop while the pump runs
• The discharge line freezes repeatedly
• The check valve installation is questionable
• The pit refills quickly and the pump can’t keep up
• You see electrical risk or the breaker trips
• You have a finished basement and want a reliable long-term setup

Additionally, if your “water” is actually a sewer backup, don’t treat it like a sump issue. Start with Video Camera Sewer Inspection and, if needed, Sewer Line Repair & Replacement.

Sump pump keeps running: prevention and maintenance checklist

To reduce the chance your sump pump keeps running again:

• Test the pump before storm season.
• Verify the float moves freely.
• Confirm the check valve works.
• Check the discharge outlet for clogs and freezing risk.
• Add an alarm (and a battery backup if you’re high risk).
• Keep the pit clean and consider a sealed lid.

If you ever deal with basement flooding, dry it quickly to reduce mold risk. EPA guidance: https://www.epa.gov/mold

FAQ

Is it normal if the sump pump runs for a long time during heavy rain?

Yes, sometimes. However, it should still lower the pit level and eventually cycle off. If it never shuts off, you need diagnosis.

Can a bad check valve really make the pump run nonstop?

Yes. Backflow can keep the pit “high enough” to trigger the float repeatedly.

Should I unplug the sump pump if it keeps running?

Only if you can do it safely and you’re sure it won’t flood. In many cases, shutting off the breaker is safer than pulling a wet plug.

Service Area (Maryland only)

Quince Orchard Plumbing serves Gaithersburg (20878), Rockville, Germantown, North Potomac, Darnestown, Montgomery Village, Potomac (north), Derwood, Kentlands, and Washington Grove.