Why Your Sump Pump Isn’t Working or Won’t Turn Off

Two opposite failures send people searching for help with a sump pump: dead silence while water creeps up the basement floor, and a motor that runs and runs and never clicks off. They look like unrelated problems. They often share a single cause. The float that tells the pump when to start and stop, and the discharge line that carries water out of the house, sit at the center of both symptoms. When one of those gets stuck, jammed, or blocked, the same part can produce either failure depending on which position it freezes in.

This guide walks the symptoms back to their causes so you can localize the fault before you touch anything. It also draws a hard line. A few checks are genuinely safe to do yourself. Anything involving the motor, wiring, or capacitor is not, especially with water rising in the pit. Standing water and electricity together are a serious shock hazard, and that combination decides where your part of the job ends.

For how the pump and its parts work in the first place, see our guide on how a sump pump works (093). This post assumes you already have a problem and want to find it.

When the Pump Stays Silent: Power, Float, and Jam Checks

A silent pump has lost either its trigger or its power. Start with power, because it is the most common and the easiest to confirm.

Check that the pump is plugged in and that the outlet has power. Sump pumps in unfinished basements are required to be on a ground-fault circuit interrupter (GFCI), and a GFCI trips on purpose when it senses current leaking to ground. A tripped GFCI or breaker is one of the leading reasons a healthy pump goes quiet. Press the reset button on the GFCI outlet, or reset the breaker, and listen for the pump to respond. If it trips again right away, stop. A breaker that trips immediately on a sump pump often points to a jammed impeller drawing too much current or a fault in the motor, and that is electrician or plumber territory, not a repeat-reset situation.

If power is confirmed, look at the float. The float is the on/off trigger, and it has to rise freely with the water. Reach in (with the pump unplugged) and check whether the float is hung up on the pit wall, pinned against the discharge pipe, or tangled with its own cord. Manufacturer troubleshooting from Zoeller lists an obstructed float and water sitting below the activation level as direct causes of a pump that will not start. Freeing a float that is caught on the basin wall is a safe thing to do. Clearing visible debris like gravel or silt from the pit is also safe.

What is not safe is going past those checks. If power is good, the float moves freely, the pit is clear, and the pump still will not run, the failure is likely inside the switch, the motor, or the wiring. That is the point to bring in a licensed plumber or electrician rather than opening the unit.

When the Pump Runs and Never Shuts Off

A pump that never stops is either being told to keep running or genuinely cannot keep up. The fix depends on which.

The first thing to rule out is a float stuck in the up (on) position. Debris in the pit, a float wedged against the basin, or water seeping into the switch can leave it permanently calling for the pump. Zoeller’s troubleshooting describes a float held up by debris and a defective switch as the two causes of continuous running. Unplug the pump and watch whether the float drops on its own as the water level falls. If it stays up while the water is clearly down, the float or switch is the problem.

If the float drops correctly but the pump still runs, look at whether water is coming back. A check valve sits in the discharge line to stop the column of water above it from draining back into the pit after each cycle. When that valve is installed backward, stuck, or failed, the same water the pump just pushed out falls back in, refills the pit, and trips the float again. The pump ends up moving the same gallon in circles. A failed check valve is a known cause, but swapping it is an install job rather than a diagnostic check, so treat a suspected bad check valve as a found cause and have it replaced properly.

The harder case is a pump that runs constantly because the water genuinely will not stop arriving. A continuously high water table, heavy sustained rain, or a pump that is undersized for the volume entering the pit will all keep a perfectly good pump working nonstop. That is not a fault to reset. It is a sizing and drainage question, and a basement that floods despite a working pump points toward a broader prevention plan covered in our guide on preventing basement water and plumbing flooding (099).

Why a Stuck or Tangled Float Causes Both Problems

The float deserves its own section because it is the single part that can produce either failure. This is the framing competitors usually miss by splitting “won’t run” and “won’t shut off” into separate articles.

Picture the float as a switch with two failure positions. If it sticks in the down position, or hangs up before it can rise, the pump never gets the signal to start, and you get silence while water climbs. If it sticks in the up position, the pump never gets the signal to stop, and you get a motor that runs without end. Same part, opposite symptom, decided entirely by where it jams.

That is why the float check belongs in both troubleshooting paths. A float can hang up on the pit wall, foul on the discharge pipe, catch on its own power cord, or get pinned by gravel and silt that wash into the pit over time. Tethered floats that swing on an arm and vertical floats that ride up a rod both jam, just in different ways. Manually lifting and lowering the float with the pump unplugged tells you fast whether it moves through its full travel. If it binds, clear what it is catching on. If it moves freely and the pump still misbehaves, the switch itself has likely failed internally, and a failed switch is a replacement rather than a reach-in fix.

When the Discharge Line Is the Real Culprit

Sometimes the pump and float are fine and the problem is downstream, in the pipe that carries water out of the house. A blocked discharge line makes a working pump look broken: the motor runs, but little or no water leaves, so the pit stays full and the float keeps the motor going.

Two things commonly block that line. A frozen discharge line in winter is a classic cause, because the pipe usually exits to the outdoors where it can ice up at the end or along an exposed run. A clogged line, from sediment, debris, or a discharge end buried in mud or leaves, does the same thing. An air-locked pump, where trapped air stops the pump from priming, and a discharge end that simply terminates too close to the house can also keep water from clearing.

Where that water is allowed to go is set by local code and matters more than people expect. Groundwater pumped from a sump should not be sent into the sanitary sewer. The U.S. Environmental Protection Agency treats basement sump pumps tied into sanitary sewers as an inflow source that overloads the system and contributes to sewer backups and overflows. Acceptable discharge points and minimum distances from the foundation vary by jurisdiction, so verify your local code before changing where the line ends. For keeping the discharge clear before storm season and through winter, see our guide on how to test and maintain a sump pump (095) and the winterizing approach in our guide on how to prevent basement water and plumbing flooding (099). Reworking the buried or outdoor run is a job for a licensed plumber.

Safe Checks You Can Make vs. When to Call a Pro

The line between what you can do and what you should hand off is set by one fact: rising water plus electricity is a shock hazard, and a GFCI exists precisely because that combination can be lethal. CPSC notes a GFCI shuts off power within milliseconds when current leaks to ground, which is what happens when water reaches something live. Respect that boundary and the rest is straightforward.

Safe to do yourself, with the pump unplugged where it makes sense:

• Confirm the pump is plugged in and the outlet has power.
• Reset a tripped GFCI or breaker once, and stop if it trips again immediately.
• Clear visible debris, silt, and gravel from the pit.
• Free a float that is caught on the basin wall, the discharge pipe, or its own cord.
• Look at the visible discharge outlet for ice, mud, or blockage.

Leave these to a licensed plumber or electrician:

• Any work on the motor, capacitor, or wiring.
• Replacing the float switch, check valve, or the pump itself.
• A breaker or GFCI that keeps tripping the moment power is restored.
• Reworking the discharge piping or where it terminates.

If the water is rising fast and you cannot stop it, the priority is safety, not diagnosis. Keep out of standing water near energized equipment and get professional help.

Frequently Asked Questions

My sump pump runs constantly and won’t shut off. What’s wrong?
Nonstop running points to one of three things. A float stuck in the on position never lets the motor get its stop signal, so unplug the pump and watch whether the float drops as the water falls. A failed check valve lets pumped water fall straight back into the pit, so the pump keeps moving the same water in circles. If the float and check valve are fine, the pit may simply be filling faster than the pump can clear it, which is a sizing or drainage question rather than a fault to reset.

Why did my sump pump stop after a power outage?
A standard sump pump runs on household current and does nothing during an outage. After power returns, check whether the GFCI or breaker tripped and needs a reset. If it has power but stays silent, the float may be stuck or the switch may have failed. An outage is also the exact moment a battery backup matters, since the storm that knocks out power is often the storm flooding the basement.

Is it safe to reach into the sump pit?
Only with the pump unplugged, and only to free a float or clear debris by hand. Never reach into a pit with the pump energized, especially if water is high. If anything needs more than that, it is time for a professional.

How long does a sump pump float switch last?
Switches wear out. Manufacturer guidance puts typical automatic float switch life in the range of several years, after which intermittent or stuck behavior becomes more likely. A switch that no longer moves the pump reliably should be replaced rather than nursed along.

This article is general information, not professional advice. For work involving electrical components or rising water, consult a licensed plumber or electrician.

Sources

U.S. Consumer Product Safety Commission, “What Is a GFCI?” (CPSC Document #099): https://www.cpsc.gov/s3fs-public/099_0.pdf
U.S. Consumer Product Safety Commission, “Easily Installed Device Protects Family Against Electrocution”: https://www.cpsc.gov/Newsroom/News-Releases/1989/Easily-Installed-Device-Protects-Family-Against-Electrocution
U.S. Environmental Protection Agency, “Sanitary Sewer Overflows (SSOs)”: https://www.epa.gov/npdes/sanitary-sewer-overflows-ssos
U.S. Environmental Protection Agency, “Sanitary Sewer Overflow (SSO) Frequent Questions”: https://www.epa.gov/npdes/sanitary-sewer-overflow-sso-frequent-questions
Zoeller, “4 Common Sump Pump Problems (and How to Fix Them)”: https://ca.zoeller.com/2024/04/15/4-common-sump-pump-problems-and-how-to-fix-them/