The short answer
When a sump pump stops working in a Northern Virginia basement, it’s almost always one of four things: no power (a tripped GFCI outlet or breaker), a stuck float, a jammed or air-locked pump, or a pump that’s worn out. What it sounds like tells you which. A hum with no water moving is a jam or a stuck float. Silence is power or the float. Running with no water leaving is the discharge pipe or the check valve. Unplug it before your hand goes in the pit, every time.
Unplug it first
A sump pit is water and a plugged-in motor in the same hole. Unplug the pump before you reach in, and if the floor around it is wet, turn the breaker off first and pull the plug with a dry hand. Then you can look.
$697 Sump Pump Replacement
A new cast iron pump in your existing pit, a quiet check valve, new pipe to the discharge, the old pump hauled away and a bucket test before we leave. See the offer
It hums, and the water doesn’t move
The motor has power, but the impeller can’t turn or the pump is spinning on air. Three usual causes:
- A jam. Gravel, a sock, a piece of debris in the intake. Unplug it, lift the pump if you can, and clear the screen.
- A stuck float. The float very often wedges against the pit wall or the discharge pipe. Work it loose and lift it by hand. If the pump runs, set it so the float swings clear. If it still only hums, the switch or the motor is finished.
- An air lock. Air trapped in the pump body keeps it from moving water. Most installs have a small weep hole in the pipe between the pump and the check valve to let that air out. If it’s plugged, clear it with a toothpick.
It won’t turn on at all
- The GFCI. Many basement pumps sit on a GFCI outlet that trips without a sound. Press reset.
- The breaker. Check it at the panel.
- The piggyback plug. Many pumps plug into the back of the float switch’s plug, which plugs into the wall. Plug the pump straight into the outlet for a few seconds. If it runs, the float switch is bad. Put the plugs back the way they were.
- The thermal overload. A pump that ran all night and is now silent and hot shut itself off to protect the motor. Give it an hour to cool. If it comes back and does it again, it’s failing or it’s too small for the job.
- The pump is done. Zoeller puts a sump pump’s service life at seven to ten years. Past that, a pump that won’t start usually needs replacing, not repair.
It runs, but no water leaves the pit
The pump is fine and the water has nowhere to go. In January it’s usually the outside end of the discharge pipe frozen shut, so the pump runs against a closed pipe. Freeze relief fittings exist for exactly this. The rest of the year it’s a blocked line, or a check valve that failed and lets the water run straight back down. If it runs and runs in a dry week, why a sump pump runs constantly walks through it.
What the noises mean
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| The noise | What it means | What to do |
|---|---|---|
| A clunk or bang when it shuts off | The check valve slamming shut. Annoying, not dangerous. | A quiet check valve ends it. How check valves work |
| A slurp at the end of each cycle | The pump pulling the last of the water and a little air. Normal. | Nothing. |
| Grinding or rattling | Debris in the impeller, or worn bearings | Unplug it and clear the intake. Still grinding: the pump is wearing out. |
| A hum with no water moving | A jam, a stuck float or an air lock | Clear the intake, work the float loose, check the weep hole. |
| Water rushing back down after it stops, or a restart thirty seconds later | A failed check valve. The pump keeps pumping the same water. | Replace the check valve. It’s a cheap part, and it saves the pump. |
Test it before the next storm
The bucket test takes two minutes. Pour five gallons of water into the pit. The float should rise, the pump should start within a few seconds, the water should drop fast, and the pump should shut off cleanly without running dry. Then listen. Water rushing back means the check valve. Do it in March and again in August, ahead of the spring rains and the late-summer storms. How the float switch works shows what you’re watching for.
Repair or replace
A float, a check valve or a tripped outlet is a repair. A motor that hums with nothing jamming it, a pump past ten years old, or one that trips its overload every storm is a replacement. Our sump pump replacement is $697 installed, normally $997: a new cast iron pump in your existing pit, a quiet check valve, new pipe to the discharge, the old pump hauled away and a bucket test before we leave. A water alarm is included. A new or deeper pit, outside discharge work, a battery backup and electrical work are extra, and you hear the price for any of those before we start.
Sump pump repair and replacement costs has the rest of the prices, and when to replace a sump pump goes through the call. If an alarm is what sent you here, what a sump pump alarm is telling you sorts the shriek from the chirp, and photos of a pump that stopped show what the plumber looks at first. For every other sound in the house, start with what house noises mean. If the pit works fine but smells like sewage or rotten eggs, why a sump pump smells sorts that out.
Book it
A plumbing diagnosis visit is $49, or $250 after hours, and you get the price of the fix before we start. Call (703) 997-9757, day or night, or book online with the problem already filled in. Every current deal is on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why does my sump pump hum but not pump water?
Something is stopping the impeller, or the pump is full of air. Unplug it, clear the intake, work the float loose and clear the small weep hole in the pipe between the pump and the check valve. If it still hums with nothing in the way, the motor is failing.
How do I reset a sump pump?
Most have no reset button. Unplug it for a minute, press reset on the GFCI outlet it uses, check the breaker, then plug it back in. A pump that shut off hot needs about an hour to cool before it will restart.
Why won’t my sump pump turn on when the pit is full?
Power first: the GFCI, the breaker, the plug. Then the float: if it’s stuck down against the pit wall or the pipe, the pump never gets the signal. If the power and the float are fine and it stays silent, the switch or the motor has failed.
Can a sump pump run without a check valve?
It will run, but every time it stops, the water in the pipe falls back into the pit and the pump pumps it again. That’s extra starts for nothing, and starts are what wear a pump out.
How long do sump pumps last?
Zoeller puts a sump pump’s service life at seven to ten years. A pump that runs a lot, sits in loose gravel or short-cycles off a bad check valve wears out sooner.
