Fix a Sump Pump That Stopped Working

Basement water pools around a silent sump pump. The float sits high, the pit fills, and nothing happens. Most sump pump failures trace to four fixable problems: stuck float switches, clogged screens, power issues, or blocked discharge pipes. Each shows clear symptoms and responds to straightforward troubleshooting. The system is simple by design. A float rises with water level, triggers a switch, and starts a pump that pushes water out through a discharge line. When any part of this sequence breaks down, water stops moving. Understanding the order of operations makes diagnosis quick. Most repairs need no specialized parts and take less time than waiting for a service call. Start at the power source and work toward the water.

1. Check Power and Reset the System. Confirm the pump is plugged in and the outlet has power by testing with a voltage tester or plugging in a lamp. Check your electrical panel for a tripped breaker and reset it if needed. Unplug the pump, wait thirty seconds, then plug it back in to clear any thermal overload protection that may have triggered.
2. Inspect and Free the Float Switch. Look at the float mechanism while the pit has water in it. The float should move freely up and down without catching on the discharge pipe, pump body, or pit walls. If it's wedged or tangled, reposition it so it has clear vertical travel. Manually lift the float to see if the pump activates. If the pump runs when you lift the float manually but won't trigger on its own, the float switch is likely failing.
3. Clear the Intake Screen. Unplug the pump and lift it out of the pit. The intake screen at the pump base catches debris. Rinse it under a hose or scrub it with a stiff brush to remove mud, gravel, and organic matter. Look inside the intake opening for anything blocking the impeller. Spin the impeller by hand to confirm it rotates freely.
4. Test the Check Valve. Locate the check valve on the discharge pipe above the pump. This one-way valve prevents water from flowing back into the pit. Remove it and look for debris or a stuck flapper. If water flows backward through it when you hold it horizontally, it's failed. Replace it with a new valve oriented with the arrow pointing away from the pump.
5. Inspect the Discharge Line. Follow the discharge pipe from the pump to where it exits the house. Look for ice blockages in winter, crushed sections, or disconnected joints. Outside, make sure the exit point isn't buried in mud or blocked by leaves. Run water through the line with a hose to confirm it flows freely to daylight.
6. Run a Full Cycle Test. Put the pump back in the pit and plug it in. Pour five gallons of water into the pit and watch the complete cycle. The float should rise, the pump should start within two seconds, and water should discharge outside. The pump should run until the water level drops and the float settles, then shut off cleanly. Time the cycle and note any unusual sounds.
7. Clean the Pit and Set Water Level. Scoop out accumulated sediment from the bottom of the pit with a shop vacuum or small bucket. Rinse the pit walls. Adjust the float rod or tether so the pump activates when water reaches four inches deep and shuts off at two inches. This range prevents short cycling while keeping the basement floor dry.
8. Document Pump Age and Runtime. Write the installation date or today's date on the pump housing with a paint marker if no date exists. Note how often the pump runs during typical rain. If it cycles more than once every ten minutes during steady rain, the pit may be undersized or there's a high water table issue that needs attention beyond the pump itself.