If your sump pump is not working, check power and the float switch first. The problem is often a tripped outlet, stuck float, debris in the pit, or a blocked discharge line. Start with the simple checks before assuming the pump is dead.
Check power safely
Make sure the pump is plugged in and the outlet has power. If it uses a GFCI outlet, check whether it tripped. Don't stand in water while handling electrical equipment.
Test the float switch
The float switch tells the pump when water is high enough to run. If it is stuck against the pit wall, tangled, or blocked by debris, the pump may not turn on. If you lift the float manually, use a broom handle or another non conductive object rather than your hand.
Test it with water
If the pit is dry enough to test safely, slowly pour about 5 gallons of water into the sump pit and watch whether the pump turns on, moves water out, and shuts off again. If the pump has a lid, remove it first so you can see what is happening.
A good test is not just whether the motor makes noise. You want to see water leave the pit and confirm the float moves freely.
Check the pit and discharge line
Look for mud, stones, or debris that could block the pump or float. Make sure the discharge line is not frozen, crushed, clogged, disconnected, or sending water right back toward the foundation.
If the pump hums but does not move water
A humming pump usually means it has power, but something is stopping it from moving water. The impeller may be jammed, the pump may be air locked, the discharge line may be blocked, or the pump may be failing internally.
Unplug the pump before reaching into the pit or handling the unit. If clearing obvious debris doesn't fix it, stop there. A pump that hums without moving water can overheat.
If the pump runs but water does not go down
Watch the pit while the pump runs. If the water level barely changes, the issue may be a blocked discharge pipe, a broken impeller, a stuck check valve, or water flowing back into the pit after each cycle.
Go outside and confirm that water is leaving the discharge point. If water exits too close to the foundation, it can cycle back toward the sump pit and make the pump run again.
If the pump runs constantly
A constantly running pump can mean heavy groundwater, a stuck float, a missing or failed check valve, or water returning from a poorly routed discharge line. It can also mean the pump is undersized for the amount of water entering the pit.
Don't ignore constant running. Even if the pump is moving water, nonstop operation can shorten its life and leave you exposed if it burns out during a storm.
Check the check valve
The check valve keeps discharged water from falling back into the pit after the pump turns off. If you hear water rushing back down the pipe, or the pump short cycles again and again, the check valve may be stuck, missing, installed backward, or worn out.
This is a common reason a sump pump seems to work but never really catches up.
Think about backup power
Storms can knock out power at the same time groundwater rises. If your basement depends on a sump pump, consider a battery backup. A water powered backup can also make sense in some homes, but only if your water supply, local rules, and plumbing setup support it.
When to call for service
- The pump has power but only hums.
- The breaker or GFCI trips repeatedly.
- The pump runs but the pit water level does not drop.
- The discharge line is buried, frozen, or hard to inspect safely.
- The pump runs constantly during normal weather.
- The pump is old and failure would mean basement flooding.
Good maintenance rhythm
- Test the sump pump before rainy season, and every few months if your basement depends on it.
- Check the pit for debris whenever you test it.
- Confirm the discharge line is clear before heavy rain or freezing weather.
- Review backup power at least once a year if the basement depends on the pump.
- Track the pump age and replacement date.