Why won't my sump pump turn on?

The three most common reasons a sump pump won't turn on: (1) The GFCI outlet has tripped — press the reset button on the outlet. (2) The float switch is stuck in the down position — lift it manually to test. (3) The pump motor has failed — if it hums but doesn't run, the impeller may be jammed or the capacitor has failed.

Why does my sump pump keep running non-stop?

Continuous running usually means one of three things: the float switch is stuck in the on position, the check valve has failed and water is draining back into the pit after each cycle, or the pump doesn't have enough capacity for the current water inflow rate (undersized pump or severe storm conditions).

My sump pump runs but water doesn't go down — why?

If the pump runs but the pit level stays high, the discharge line is likely blocked (frozen pipe, debris, or a closed valve), the impeller is damaged or clogged, or the pump capacity is too small for the inflow rate. Check the discharge outlet outside for ice or blockage first.

How do I know if I need a new sump pump or just a repair?

Repair is usually worthwhile if the pump is under 7 years old and the failure is a float switch or check valve (both cheap fixes). Replace if the motor makes grinding noises, the pump is over 7–10 years old, or it has failed twice in the past two seasons. The cost of a float switch replacement ($20–$40) is always worth trying before buying a new $150–$200 pump.

Sump Pump Not Working? Here's How to Fix It

Most sump pump failures come down to five problems — and four of them are fixable in under an hour without calling a plumber. Here's how to work through each one systematically.

Homeowner inspecting basement mechanical equipment

Quick Diagnosis: What Symptom Do You Have?

Symptom	Most Likely Cause	Fix
Won't turn on at all	Power issue or stuck float	Check GFCI, test float manually
Runs but doesn't stop	Failed check valve or stuck float (on)	Replace check valve, adjust float
Runs but water level stays high	Blocked discharge or failed impeller	Clear discharge, inspect impeller
Hums but doesn't pump	Jammed impeller or capacitor failure	Clear jam or replace pump
Loud grinding/rattling	Debris in impeller or bearing failure	Clear debris or replace pump
Intermittent operation	Loose wiring or failing motor	Check connections, test motor

Problem 1: Pump Won't Turn On

Step 1: Check the Power

This sounds obvious, but power issues cause roughly 30% of "broken" sump pump calls:

Confirm the pump cord is plugged in securely.
Find the GFCI outlet (usually the wall outlet in the utility area). Press the reset button. GFCI outlets trip on moisture — common in basements.
Check the circuit breaker panel. A tripped breaker serving the basement outlet will look slightly off-center. Flip it fully off, then back on.

Step 2: Test the Float Switch

Remove the pit cover. Lift the float manually to its triggered position. If the pump activates, the float switch is functioning — it was just stuck or set too high. If the pump doesn't activate when you manually trigger the float, the motor itself is the problem.

Float switches get stuck for several reasons:

Debris (gravel, silt) collecting under the float
The float arm tangled on the pump housing or discharge pipe
Float positioned too high (triggers too late)

A replacement float switch costs $15–$35 and takes 20 minutes to swap. Try this before buying a new pump.

Step 3: Test the Motor Directly

If power is confirmed and the float tests fine, but the pump still doesn't run, plug the pump directly into a known-working outlet (using an extension cord temporarily). If nothing happens, the motor has failed. At that point, replacement makes more sense than repair.

Problem 2: Pump Won't Stop Running

Continuous running is the second most common complaint — and it will burn out a motor in days if uncorrected.

Failed Check Valve

The most common cause: the check valve has failed open, allowing water to drain back into the pit after each pump cycle. The float re-triggers before it can fall, and the pump runs indefinitely.

Test: After the pump runs and shuts off, watch the pit level for 30 seconds. If it rises quickly without rain actively entering, the check valve is leaking back. A replacement check valve costs $10–$25 and takes 15 minutes to swap.

Float Stuck in On Position

The float may be wedged against the pump housing or discharge pipe in the triggered position. Open the pit and check visually. Reposition the pump so the float has clear vertical travel.

Undersized Pump During Severe Rain

If it's actively pouring and the pump runs non-stop without the pit overflowing, the pump is handling the load — that's normal behavior during peak inflow. If the pit is still rising while the pump runs constantly, you need a higher-capacity pump for your conditions. See our sump pump rankings for sizing guidance.

Problem 3: Runs But Doesn't Pump Water Down

Blocked Discharge Line

Check the discharge pipe exit outside the house. Common blockages:

Ice: In winter, the pipe can freeze solid at the exterior terminus. A pipe freeze in January is a top cause of basement flooding. Install a freeze protection fitting or ensure the exit has a slight downward slope.
Debris: Leaves, mud, or animal nests can plug the pipe end. Clear with a plumber's snake or garden hose.
Closed valve: If someone manually closed a shutoff valve in the discharge line, the pump can't push water through.

Clogged or Damaged Impeller

Unplug the pump. Remove it from the pit. Turn it upside down and look into the intake screen at the base. Gravel, silt, or debris can jam the impeller. Clear it with needle-nose pliers. Spin the impeller manually with a screwdriver — it should rotate freely. If it's seized or broken, replace the pump.

Problem 4: Humming But Not Pumping

A humming pump that doesn't move water is usually a jammed impeller or a failed start capacitor. Try clearing the impeller as above. If the impeller is clear but the motor hums without starting, the capacitor has failed — this is a $5–$15 part on some models, but disassembling the motor housing of a sealed submersible pump is not practical for most homeowners. Compare repair cost vs. a new pump.

Problem 5: Loud or Unusual Noises

Noise	Likely Cause	Action
Grinding	Debris in impeller, bearing failure	Clear debris; replace if grinding persists
Rattling	Loose pump in liner, debris in impeller	Reposition pump, clear intake
Banging (on shutoff)	Water hammer from missing check valve	Install/replace check valve
Squealing	Bearing wear	Replace pump — bearing failure is terminal

When to Replace Instead of Repair

Replace the pump if any of these apply:

The pump is 7+ years old — even if you fix it today, another failure is likely soon
The motor makes grinding or squealing noises even after clearing debris
It has failed twice in the same season
The pump failed during active flooding (don't rely on it again after a stress failure)

The cost of a replacement pump ($160–$200 for a quality unit) is always less than the cost of a single basement flood. Don't patch a dying pump.

Prevention: Avoid the Next Failure

Test your pump every six months (pour a bucket, confirm it activates)
Clean the intake screen annually
Check the check valve function annually
Add a battery backup — the most common failure scenario is a power outage during a storm
Install a water alarm in the pit (sump pump alarms explained)

Related Guides

If your pump needs replacing, see the 2026 sump pump rankings for current recommendations. For step-by-step replacement, follow the DIY installation guide. Protect against power outage failures with a battery backup unit. Use the Cost Calculator to budget for pump replacement plus backup system.