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Sump Pump Not Working? Signs It's Failing and What to Check

Updated November 1, 2026 · General information, not plumbing or electrical advice

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The short answer: Check the power first (plugged in, breaker, outlet), then the discharge pipe, then the pit and float. Pour water into the pit to test. If the pump sounds like it is pumping gravel, the float is sluggish or it won't start, it may need a new float or a new pump (NDSU Extension). Replace rather than keep repairing an old pump.

Safety first. Sump pumps run on household power in a wet place. Unplug the pump before you handle it, stay out of standing water that is near outlets, a panel or appliances, and hire a licensed electrician or plumber for wiring and plumbing work. Check local codes and permit rules. This safety note is ours, not from a source.

Signs your sump pump is failing

It doesn't turn on when the pit is full. Check power and the float first.
It sounds like it is pumping gravel, or the float is sluggish (NDSU Extension).
It won't turn on until you lift the float, or turns on slowly. NDSU says a float switch that doesn't make good electrical contact turns on slowly or not at all.
It has been running for many years. Boston's useful-life estimate is 7 to 10 years.
Water is in the basement. Treat it as an emergency if water is near outlets or the panel; stay out and call a licensed electrician.

Common causes (Ann Arbor)

Cause	What to look at
Loss of power	Blackout, blown fuse or tripped breaker, damaged cord, or the pump was unplugged.
Float switch failure	The float catches or sticks.
Pump burnout	Worn bearings (NDSU Extension says damaged or rusted bearings are a common cause).
Clogging	Debris in the pit or at the pump inlet.
Check valve failure	Water falls back into the pit and the pump cycles more than needed (NDSU Extension).
Discharge pipe blocked	Debris or freezing.
Too much water	The pump can't keep up with the inflow.

Source: City of Ann Arbor, Sump Pump Backup Options; NDSU Extension.

How to test it (NDSU Extension)

Check that the discharge pipe outside isn't plugged and directs water away from the house.
Make sure the pump is plugged in. Remove the lid and use a flashlight to look for material that could plug the pump.
If the pit is dry, lift the float for about 10 seconds to see if the pump runs smoothly, then lower it slowly. Or pour water in slowly until the float turns the pump on, trying to match the usual inflow speed. If water doesn't normally flow in and the tile inlet is near the bottom, NDSU says to temporarily plug the inlet first.
Watch the float and listen. Make the pump turn on and off at least twice.
If you have an electric backup pump, check it the same way.

NDSU Extension suggests checking the pump before storm season, noting that many pumps have not run for a year or more and spring storms can change that quickly.

Repair or replace?

Repairable: a stuck or poor-contact float, a plugged inlet or discharge pipe, an unplugged cord, a tripped breaker. Ann Arbor says a faulty float switch can be changed relatively cheaply.
Usually replace: bearings that are rusted or damaged, a burned-out motor, or a pump near the end of the 7 to 10 year range that keeps having problems. See replacement and installation.
Call a licensed plumber if you aren't sure. NDSU Extension suggests it for a homeowner who is new to sump pumps.

Don't wait for the next failure

A backup keeps the basement dry when the power goes out or the main pump fails. Read the pros and cons of battery, water-powered and generator options first.

Battery vs water-powered backup Browse battery backup pumps

Need a pro to check it?

Boston's flood guidance says a sump pump and basin should be installed by a licensed professional. Get at least three written quotes and ask about permits.

Replacement and installation guide Find a licensed plumber

Common questions

Why is my sump pump not working?

Ann Arbor lists these causes: loss of power (a blackout, blown fuse, tripped breaker, damaged cord or being unplugged), a float switch that catches or sticks, pump burnout, clogging with debris, overwhelming volumes of water, check valve failure, and a discharge pipe blocked by debris or freezing. NDSU Extension adds damaged or rusted motor bearings.

How do I test a sump pump?

NDSU Extension says to confirm the discharge pipe isn't plugged and the pump is plugged in, check the pit for debris, then pour water slowly into the pit until the float turns the pump on. Make it turn on and off at least twice. If the pump sounds like it is pumping gravel or the float is sluggish, you may need a new pump or float.

Can I test a dry sump pump without water?

NDSU Extension says that if the sump is dry you can lift the float for about 10 seconds to see whether the pump turns on and runs smoothly, then lower the float slowly. It says briefly running a pump when it's dry will not do any damage.

Is it cheaper to repair or replace?

Ann Arbor notes that a faulty float switch on a primary pump can be changed relatively cheaply. But Boston estimates a sump pump's useful life at 7 to 10 years, so an older pump with a failing part may be nearer the end of its life. Ask a licensed plumber.

Should the sump pump run constantly?

We found no extension or government page that says how often a normal pump runs. NDSU Extension does say water flowing back through a missing check valve can make the pump cycle more than needed. If yours runs nonstop or cycles rapidly, check the discharge pipe and check valve and call a licensed plumber.

Related guides

Sources

Free printable: Sump Pump Fall Check

A ten-minute test before the wet season. Download the one-page PDF now, or get it by email along with a short series of five helpful emails.

Download the PDF