Sump Pump Running Constantly? How to Tell What's Normal and What's Wrong

“Running constantly” can mean three very different things, and the fix for one can make another worse. Buying a bigger pump will not free a stuck float. Moving the discharge will not help an air lock. So before anything else, take a flashlight to the pit and answer one question: is the pump actually moving water?

• It runs and moves water. The level holds or falls and water comes out of the discharge outside. The pump is working; the question is why so much water is reaching the pit. Causes: heavy rain, a high water table, the discharge soaking back to the foundation, a hidden source, or a pump too small for the inflow.
• It runs but moves no water. The pit is empty and the motor keeps going, or the pit is full and nothing comes out outside. This is mechanical: a stuck float switch, an air lock, a check valve stuck shut, or a frozen or blocked line. It can burn out a pump, so it is the urgent one.
• It short-cycles. It turns on and off every few seconds or every minute or two, even when not much water is coming in. Causes: too little float travel, a failed check valve letting the discharge water fall back, or a basin too small for the pump.

Last reviewed: September 24, 2026

If the pump is moving water and the level holds or falls, the pump is not the problem; the amount of water is. These are the usual sources, roughly in order of how often they are the answer.

A sump collects water from the drain tile around the footing, and that drain tile sits in the ground at about the same depth as the water table. When groundwater rises, water flows into the tile and the pit continuously. The USGS notes that groundwater levels in many US aquifers follow a seasonal cycle, typically rising in winter and spring and falling in summer and fall. That is why many pumps run nearly nonstop in March and hardly at all in August.

That pressure from saturated soil is also what pushes water through basement walls and floors; see hydrostatic pressure in basements. In a house with a high water table, a pump that runs often in a wet season is keeping the basement dry, which is its job.

This is the cause most often missed. If the discharge pipe ends right beside the house, the water soaks into the loose backfill against the foundation, flows down to the drain tile and comes back to the pit. The pump keeps lifting the same water, often every few minutes in dry weather. Check where the pipe actually ends outside; it may have come apart, been cut short by a mower, or drain into a splash block that sends water back toward the wall.

A common target is to discharge at least 10 feet from the house onto ground that slopes away, the same distance NC State Extension gives for downspouts. Local rules on where sump water may go vary, and some municipalities do not allow it into the sanitary sewer or across a property line, so check before rerouting.

If the pit fills steadily in a dry spell and the discharge is far from the house, look for water you are adding. A leaking water service line or buried irrigation pipe can feed the drain tile all year. A simple check: with every fixture and appliance off, watch the water meter for 15 to 30 minutes. If it moves, water is going somewhere. Also check for dehumidifier, air-conditioner condensate or laundry lines draining into the pit.

A pump rated at a high flow at zero lift may deliver half that when it has to push water 10 feet up and out. If the level rises during every heavy rain even though the pump never stops, it is at capacity. Pumps also lose output as impellers wear. Measure the inflow as shown above and check it against the sizing calculator; if the pump is working this hard every season, a backup pump is worth considering too (see battery vs water-powered backups).

This is the pattern that ruins pumps. A submersible pump is cooled by the water around it and the water moving through it. Running with an empty pit or against a blocked line lets it overheat. Liberty Pumps' troubleshooting table lists the causes for a pump that runs but will not turn off, and one that runs or hums but does not pump. They map onto what you can see:

Short-cycling means lots of starts with very little water moved each time. Motors and switches wear by the number of starts, so a pump that starts 60 times an hour ages far faster than one that runs once for a minute. The sizing calculator flags a basin that refills in under a minute at peak inflow for this reason.

Most constant-running problems are fixed for the cost of a part: a float, a check valve, or a few lengths of pipe to carry the water farther away. A worn or undersized pump is a replacement, and if you are unsure how much life yours has left, see how long sump pumps last.

A bigger pump is the right answer when measured inflow in heavy rain is close to what the current pump delivers at its lift, and the level still rises. If the pump runs for weeks at a time even so, the drainage around the house may need a closer look; see basement drainage systems for what those involve. Any system change is worth an on-site assessment rather than a guess.