# Sump pump not working: what to check

Updated: 2026-10-24 · https://pros411.com/en/guides/plumbers/sump-pump-not-working

## Short answer

Check the power first: is it plugged in, and did the GFCI outlet or the breaker trip? Press Reset from a dry floor. Then unplug the pump and look at the float: if it is stuck against the pit wall or caught on the cord, free it. Plug it in and pour a bucket of water into the pit. If it hums but does not pump, or does not start, call a plumber.

> Safety first: If the basement floor is wet, do not step in the water or touch the pump, the cord or the outlet. Turn off the basement circuit at the panel only from a dry spot, or call the power company. Always unplug the pump before you put your hands in the pit.

## How to check a sump pump that will not run

![Cartoon sump pump in a basement pit with water rising to the rim and a stuck float](https://pros411.com/img/guias/sump-pump-not-working.webp)

1. **The pit fills and the pump does nothing.** The water keeps rising toward the rim and the pump stays quiet. Most of the time the problem is the power or a stuck float.
2. **Press Reset on the outlet, from a dry floor.** Sump pumps usually plug into a GFCI outlet that can trip. Press its Reset button and check the breaker. Only do it with dry feet.
3. **Unplug it, then free the float.** The float tells the pump when to start. If it is stuck against the pit wall or tangled in the cord, it never rises. Free it so it moves.
4. **Plug it in and test it with a bucket.** Pour a bucket of water into the pit. The float should rise, the pump should start and the water level should drop within seconds.
5. **The water goes out through the line.** Outside, the water should come out of the discharge line and drain away from the house. Clear leaves, snow or ice from the end of the line.

## If it runs but does not pump

- The intake screen at the bottom is clogged with mud or gravel: unplug it, lift it out and rinse it.
- The check valve on the discharge line is stuck, so the water falls back into the pit.
- The discharge line is frozen or clogged outside.
- The motor is worn out: if it hums but no water moves, it needs replacing.

## If it never stops running

A float stuck in the "up" position, a failed switch or a pump too small for the water coming in. A pump that never rests wears out fast, so have a plumber check it.

## Be ready for the next storm

- Test the pump every few months with a bucket of water.
- A battery backup sump pump keeps working when the power goes out, which is often when storms hit.
- If your basement floods often, keep a spare pump on hand.

## When to call a plumber

- The pump hums or runs but the water level does not drop.
- Water is already on the basement floor.
- It will not start even with power and a free float.
- It runs nonstop, or turns on and off every few seconds.
- The pit fills after every rain faster than the pump can keep up.

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## Frequently asked questions

### Why is my sump pump not turning on?

Usually no power (a tripped GFCI outlet or breaker, or an unplugged cord) or a stuck float. If it has power and the float moves freely but it still does not start, the switch or the motor failed.

### How do I test a sump pump?

Pour a bucket of water into the pit until the float rises. The pump should start, empty the pit in seconds and shut off on its own.

### Is there a reset button on a sump pump?

Most pumps do not have one, but the GFCI outlet they plug into does. Press Reset on the outlet from a dry floor, and check the breaker.

### What happens if my sump pump fails during a storm?

Water rises in the pit and can flood the basement within hours. Move things off the floor, keep away from water near outlets and call a plumber.

### How long does a sump pump last?

Often 7 to 10 years, less if it runs a lot. A pump that is old, noisy or slow is worth replacing before the rainy season.

### Do I need a battery backup sump pump?

If your basement takes on water during storms, yes. Storms knock out the power exactly when the pump is needed most.