How to test a sump pump

Pour a bucket of water into the pit and watch: the pump should start on its own, empty the pit quickly and shut off. Wayne's manual says to inspect the pump 3 to 4 times a year, so test it in spring and fall and before heavy rain.

Why test it at all

A sump pump sits unused for weeks, then has to work during the worst storm of the year, often when the power is shaky. The only way to know it will start is to make it start. In the Chicago area, the big tests usually come with spring snowmelt and heavy spring rains, so the most important check is before that, with another in fall.

Wayne's manual for its submersible sump pumps says to inspect the pump 3 to 4 times a year for pump movement and debris on the switch or float. NDSU Extension advises checking it before the spring thaw. Your pump's own manual comes first if it says something different.

Safety first

A sump pump is an electric motor in water. Never reach into the pit while the pump is plugged in. InterNACHI suggests moving the float with something non-conductive instead. Wayne says to always unplug the pump before servicing or adjusting it, and never to walk on a wet basement floor until the power is off. If the electrical panel is in a flooded basement, call an electrician.

How to test a sump pump, step by step

1. Check the discharge pipe outsideMake sure the outlet isn't buried, frozen or blocked and that it carries water away from the house.
2. Check the powerMake sure the pump is plugged in and the GFCI outlet hasn't tripped. Press reset if it has.
3. Look into the pitLift the lid and shine a light in. The pump should be standing upright, with nothing that could jam the float or block the inlet screen. Unplug the pump before you remove any debris.
4. Pour in waterPlug the pump back in and pour water slowly into the pit, about as fast as water normally flows in, until the float rises and the pump starts.
5. Watch it run and stopThe pump should empty the pit quickly and shut off on its own. Repeat so it turns on and off at least twice, as NDSU suggests. Listen for grinding or rattling.
6. Listen after it stopsWater rushing back into the pit after the pump shuts off can mean the check valve isn't holding.
7. Test the backup, if you have oneFollow the backup pump's manual, including any test button it has. NDSU says a backup can be checked the same way as the main pump.

The parts worth a look

The outlet and cordWayne's manual says the pump should be plugged into a working GFCI outlet with the cord in good shape, and warns that a GFCI in a damp area can trip and shut the pump off. Check it and reset it if needed.
The float or switchIt has to move freely. A pump that has tilted or shifted can pin the float against the side of the pit. Wayne says some tethered float switches should be replaced every 2 years; check your manual for yours.
The check valveA one-way valve in the discharge pipe above the pump. It keeps pumped water from falling back into the pit; without it, InterNACHI says, the pump has to work twice as hard. If the pump turns on and off too often, Wayne's manual says to examine the check valve and replace it if needed.
The discharge line outsideNDSU says to make sure the pipe outside isn't plugged. Wayne's manual says the water should end up at least 3 feet from the foundation, and a line exposed to freezing should slope down and away so it drains and doesn't freeze. Clear snow and ice off the outlet in late winter.
The inlet screenClear small stones and debris from the screen at the bottom of the pump.

Backup pumps and alarms

Wayne recommends an independent high-water alarm or backup pump where high water could damage property. InterNACHI describes two kinds of backup: a battery-powered pump and one that runs on the home's water pressure. NDSU says a backup can be checked the same way as the main pump, and that battery maintenance is very important. Follow the backup's manual for its test, including any test button, and keep a battery backup's battery charged and replaced when it wears out.

When to call a pro

NDSU says a pump that sounds like it's pumping gravel, or a float that's sluggish, may mean you need a new pump or float. Call a plumber if the pump doesn't start, runs but doesn't empty the pit, won't shut off, or hums without moving water. InterNACHI also says to get professional help if the pump doesn't activate during a test. If you're new to sump pumps, NDSU suggests having a licensed plumber check it before the spring thaw.

Questions people ask

How often should you test a sump pump?

Wayne's manual says to inspect the pump 3 to 4 times a year. At minimum, test it before spring snowmelt and heavy rains, and again in fall.

How do I know if my sump pump is working without water in the pit?

Pour water into the pit until the float rises. NDSU also says that if the pit is dry you can lift the float for about 10 seconds to see whether the pump turns on and runs smoothly. Use something non-conductive, never your hand.

Why does my sump pump turn on and off so often?

A check valve that isn't holding can let water fall back into the pit, so the pump keeps re-pumping it. Wayne's manual says to examine the check valve and replace it if needed. A stuck or badly set float can also cause it.

Should a sump pump be on a GFCI outlet?

Many pump makers, including Wayne, call for a GFCI-protected outlet. Wayne also warns that a GFCI in a damp area can trip and shut the pump off, so check it regularly and reset it if needed.

Related guides

Sources

General guidance for a typical house, checked against the sources above on October 15, 2026. Your appliance's own manual, local codes and a licensed pro come first. Smell gas? Leave the house and call your gas company or 911 from outside.