Note the date; annual testing before winter is the useful habit
Homeowner guide · About 20 minutes
How to test a sump pump properly
To test a sump pump properly, know that lifting the float and hearing the motor hum only proves the motor runs. It does not prove the system moves water out of the building.
Short answer
Pour water into the pit until the float starts the pump on its own, then walk outside and confirm water is actually leaving the far end of the discharge line. That single test exercises the float, the pump, the check valve and the entire discharge as one system. Repeat it with the primary pump unplugged to test the backup. Do this in autumn, while there is still time to correct whatever it reveals.
Safety first
A sump pump is an electrical device sitting in water. If the cord, plug or outlet is damaged, wet or not protected by a GFCI, stop. Have an electrician look at it instead of operating the pump.
Before you start
What you need
- A bucket or hose
- A flashlight
- A phone to photograph the pit and outlet
Step by step
8 steps.
- 01
Look before you test. Take the lid off and shine a light into the pit. Note the water level, whether the basin holds debris or silt, whether the float can swing freely and whether the discharge pipe and check valve look sound. Photograph it so you have a dated record of the starting condition.
- 02
Fill the pit with water. Add water with a bucket or hose until the level rises and the float starts the pump by itself. This is the part that matters: you are testing whether the switch actually triggers, not whether the motor spins when you lift it by hand.
- 03
Confirm the pump moves water. Watch the level in the pit drop and listen for the pump to shut off on its own at the low point. A pump that runs but does not lower the water, or that fails to shut off, has a problem you want to find now.
- 04
Walk outside to the outlet. Go to the far end of the discharge line while the pump is running and confirm water is actually coming out. This is the step almost everyone skips, and a blocked, frozen, crushed or disconnected line is exactly what it catches.
- 05
Check the check valve. After the pump stops, listen for a significant volume running back into the pit. A little is normal; a lot suggests the check valve is failing, which makes the pump cycle more than it needs to and shortens its life.
- 06
Test the backup on its own. Unplug the primary pump, then repeat the fill test so the backup has to carry the load by itself. Confirm it starts, moves water and that its battery is holding a charge. Note the battery's age while you are there.
- 07
Check the alarm. If a high-water alarm is fitted, raise the water enough to trigger it and confirm it sounds, and that any remote notification actually arrives. An alarm nobody hears is not protection.
- 08
Plug everything back in. Reconnect the primary pump and confirm it is running on its own dedicated, GFCI-protected outlet, not an extension cord. Replace the lid and record the date of the test.
What each result means
A test is only useful if you know what to do with the outcome. Most failures show up in one of a few places, and each has a different fix. Write down what you saw, because the date and the result, kept somewhere you will actually find them next autumn alongside the pump's age and the battery's installation date, are what make next year's test mean something. Keep it simple.
If the primary pump passes and the backup does not, treat that as a real finding. The backup exists for the day the primary fails, so a backup that has never been run is a guess. Run it.
| What you saw | What it points to | What to do |
|---|---|---|
| Pump does not start when the pit fills | Float stuck, switch failed or no power | Check the outlet and float travel before replacing anything |
| Pump runs but the water level barely drops | Clogged intake or worn impeller | Have the pump pulled and inspected |
| No water at the outlet | Blocked, frozen, crushed or disconnected discharge | Trace the line from the pit to the outlet |
| Large backflow after each cycle | Failing check valve | Replace the valve; it also shortens pump life |
| Backup will not run alone | Dead battery or wrong float height | Service the backup before the wet season |
After the check
What to do with the result
Photograph the outlet so you can recognise when snow or ice has buried it
Record the pump's age: replacement is better planned than discovered mid-storm
If anything failed the test, get it corrected before the wet season rather than after
Common questions
How to Test a Sump Pump
How often should I test my sump pump?
At least once a year, and autumn is the practical time in Vermont because it leaves room to correct whatever the test reveals before snowmelt. If the pump runs frequently, or the basement is finished, testing twice a year is reasonable.
Is lifting the float enough of a test?
No. Lifting the float tests only the motor. It does not confirm the switch triggers at the right level, that the check valve holds, or that the discharge line is clear to its far end. Filling the pit tests all of those at once.
What if water does not come out of the discharge?
Stop and investigate before the next storm. The usual causes are a line blocked by ice, silt or debris, a crushed or disconnected section, or an outlet buried under snow or soil. A pump that cannot discharge is a pump that will not protect the basement.