Sump Pump Not Working: What to Check Before the Basement Floods
A sump pump that won't start, hums or runs nonstop can leave a basement exposed to the next storm. This guide covers the common causes, safe checks to run first, what not to do around water and electricity, and when to call a plumber. LocalRepairLine is a referral service, not a contractor, and this is general information, not a substitute for an in-person inspection.
Safety first
Don't step into standing water in a basement if outlets, cords or the electrical panel could be wet. If water is rising and you can reach the breaker panel only through water, stay out and call your electric utility or emergency services. Never touch a sump pump or its cord with wet hands or while standing in water. Don't run a pump dry.
What usually goes wrong
- No power. The pump is unplugged, a GFCI outlet has tripped, or the breaker has tripped.
- The float is stuck. The float arm or switch can jam against the pit wall, the pipe or debris, so the pump never starts, or never shuts off.
- A clogged intake. Silt, gravel or small debris can block the pump inlet screen, so it runs but moves little water.
- A failed check valve. If water falls back into the pit after each cycle, the pump cycles over and over.
- A blocked or frozen discharge line. The water has nowhere to go outside.
- An old or burned-out motor. Pumps wear out, especially if they run often.
Safe checks to run first
- Check the power. Confirm the plug is firmly in the outlet and press RESET on a GFCI outlet if it has one. Check the breaker once.
- Look into the pit with a flashlight. Can the float move up and down? Remove any debris you can see with a tool, not your hand.
- Do the bucket test. Slowly pour a bucket of water into the pit. The float should lift, the pump should start and the water should drop. If nothing happens, the problem is the switch, power or pump.
- Listen. A hum without pumping can mean a jammed impeller or failed motor. Unplug the pump before touching anything.
- Check outside. Make sure the discharge pipe outlet is open, not buried, and not frozen. Clear snow, leaves or ice around the end of it.
- Check for a backup. If the power is out, a battery backup pump may be the only thing keeping the pit from overflowing.
What not to do
- Do not use an extension cord that's lying in water.
- Do not run the pump dry for long.
- Do not ignore a pump that cycles constantly or makes grinding noises.
- Do not wait for the basement to flood before testing the pump.
When to call a plumber
- Water is standing in the pit and the pump won't start after the checks.
- The pump hums, smells hot or trips the breaker again after a reset.
- The pump runs nonstop or cycles every few seconds.
- The pump is old, and you want it tested before the rainy season.
- Water is entering the basement from other places.
Keep it ready for the next storm
- Test the pump with a bucket of water every few months and before heavy rain.
- Keep the pit clean and the lid in place.
- Ask a plumber about a battery backup so a power outage doesn't leave you without a pump.
What to tell the plumber
- The age and brand of the pump, if you can see it.
- Whether it hums, runs constantly, or doesn't start at all.
- What you checked: power, float, bucket test, discharge line.
- Whether there's standing water in the basement.
Need a plumber?
Describe the problem to an independent local plumbing company. A short automated prompt plays first, and then you're connected. LocalRepairLine is a referral service, not a contractor.
Plumbing repair by city
Philadelphia, PA · Pittsburgh, PA · Columbus, OH · Cleveland, OH · Cincinnati, OH · Toledo, OH · Denver, CO · Grand Rapids, MI · Fort Wayne, IN