Why Is My Sump Pump Running Constantly? How to Tell a Problem From a Wet Season
After heavy rain, a sump pump that cycles every few minutes is doing its job. A pump that runs with an empty pit, or refills itself the moment it stops, is telling you something else.
Quick answer
First look in the pit. If water keeps pouring in after rain or snowmelt, the pump is working as designed. If the pit is empty and the pump still runs, the float switch is stuck or failed. If the pit refills right after the pump shuts off, the check valve is probably letting the discharged water fall back in. A pump that runs but moves no water may be air-locked or clogged.
- Difficulty
- Moderate DIY
- Look first
- Is water actually coming into the pit?
- Most common fault
- Float stuck on, or a failed check valve
- Safe to DIY
- Clear the pit, free the float, test with a bucket of water
- Plumber or electrician
- Replacing the pump, switch or check valve; any wiring
On this page
A sump pump sits in a pit at the lowest point of a basement or crawl space. Drain tile around the foundation carries groundwater into the pit. When the water rises, it lifts a float; the float switch starts the pump; the pump pushes the water up a discharge pipe and out of the house; and a one-way check valve keeps that water from falling back down when the pump stops.
“Running constantly” can mean any of those parts is doing too much or too little. The trick is to watch one full cycle.
Watch one cycle: what you see tells you the cause
- Lift the pit cover and look.
Is water flowing into the pit from the inlet pipes or the sides? If the pit fills steadily after rain or snowmelt, the pump is keeping up with real water. That is normal.
- Watch the pump stop.
When the water drops, the float should fall and the pump should switch off. If the water is low and the pump keeps running, the float is stuck or the switch has failed.
- Listen and watch right after it stops.
If you hear water rush back down the pipe and the pit level jumps, the check valve is not holding. The pump will restart soon after, pumping the same water again.
- Check the discharge outside.
Water should come out of the discharge pipe while the pump runs, and drain away from the house. If it runs but little comes out, the line may be clogged, frozen or the pump air-locked.
The six causes, by symptom
| What you see | Likely cause | What to do |
|---|---|---|
| Pit keeps filling, pump cycles normally | Heavy rain, snowmelt or a high water table | Normal. Make sure discharge drains well away from the foundation |
| Pump runs with the pit nearly empty | Float stuck in the on position by debris, the pit wall or the pump’s own cord | Unplug, clear debris, reposition the float so it moves freely |
| Pump runs, float moves freely, still will not stop | Failed float switch | Replace the switch (or the pump, if the switch is built in) |
| Pit refills seconds after the pump stops; water rushes back | Check valve stuck open, worn or missing | Replace the check valve; check the arrow points away from the pump |
| Pump hums or runs but little water leaves | Air lock, clogged intake or impeller, blocked or frozen discharge line | Check the vent hole, clean the intake screen, clear the line |
| Runs often in dry weather | Underground leak, discharge draining back toward the house, pit too small | Look for leaks; extend the discharge; ask a plumber about the pit |
The float
Most pumps use a tethered float that swings up and down, or a vertical float that slides on a rod. Both can hang up on the side of a small pit, the pump’s power cord, or debris such as gravel and silt. Unplug the pump, then reach in with gloves and move the float through its full range by hand. It should rise and fall freely and click the pump on and off when you plug it back in and test it with a bucket of water.
The check valve
A check valve that sticks open lets the water standing in the vertical pipe drain back into the pit as soon as the pump stops. The float rises again and the pump restarts, a loop that can repeat all day. The giveaway is a gush of water back into the pit and a pump that restarts after a short pause. Check valves are inexpensive but sit in a pressurized line, so many homeowners have a plumber replace them.
Air lock and the vent hole
When a check valve is installed, Zoeller’s instructions call for a small hole, about 3/16 inch, drilled in the discharge pipe below the valve and below the pit cover. It lets trapped air escape so the pump can prime. If that hole clogs, the pump can spin without moving water. You will see a small spray from it while the pump runs; that is normal.
Unplug the pump before you touch anything in the pit, and never stand in water while handling a plugged-in pump or its outlet. If the basement is flooded around the outlet or panel, call your utility or a licensed electrician to cut power first.
Keep it ready for the wet season
- Test it with a bucket of water a few times a year and before spring and fall rains.
- Keep the pit clear of silt, gravel and debris.
- Make sure the discharge carries water well away from the house, and that it cannot freeze shut or drain back toward the foundation. IBHS suggests directing downspouts 3 to 4 feet away from the foundation; discharge lines deserve the same attention.
- Plug the pump into a grounded, GFCI-protected outlet on its own circuit, never an extension cord.
- Consider a battery backup pump and a high-water alarm. A sump pump is most needed during storms, which is also when the power goes out.
When to call a plumber
- The pump is around 7 years old, the typical life InterNACHI lists for sump pumps, and is failing in more than one way. The repair or replace calculator helps with that call.
- The check valve needs replacing and you are not comfortable cutting and refitting the discharge pipe.
- The pit is too small, so the pump short-cycles even with a working float and valve.
- Water is coming in faster than one pump can handle, which can call for a larger pump, a second pump or drainage work.
Frequently asked questions
Is it normal for a sump pump to run every few minutes?
During and after heavy rain or snowmelt, yes. Groundwater around the foundation can feed the pit steadily for hours or days. The pump should start when the water reaches the float’s trigger level, empty the pit and stop. If it cycles with little or no water coming in, look at the check valve and float.
Can a sump pump run too much and burn out?
Yes. Constant running, especially with too little water to cool the motor, shortens a pump’s life. A pump that never shuts off with an empty pit should be unplugged and looked at, as long as water is not about to rise in the basement.
How do I test my sump pump?
Slowly pour a bucket of water into the pit. The float should rise, the pump should start, empty the pit and switch off on its own. Do this a few times a year and before the wet season.
Why does my sump pump run when it hasn’t rained?
A high water table, a nearby underground leak (from a water main, irrigation line or your own supply pipe), snowmelt, or discharge water that drains straight back toward the house can all keep a pit filling without fresh rain. A failed check valve can also make a pump recycle the same water.
Should a sump pump be on a GFCI outlet?
Sump pump makers recommend a grounded, GFCI-protected outlet that is not controlled by a wall switch, on a circuit sized for the pump, and no extension cord. Because a tripped GFCI silently stops the pump, a water alarm in the pit is a good backup.
Sources
- 4 Common Sump Pump Problems (And How to Fix Them) Zoeller Pump Company (Canada)
- Owner’s Manual, Models 4404 and 4405 (service checklist and vent hole guidance) Zoeller Pump Company
- Standard Estimated Life Expectancy Chart for Homes International Association of Certified Home Inspectors (InterNACHI)
- Winter Ready: How to Protect Your Home From Winter Weather (checklist) Insurance Institute for Business & Home Safety (IBHS)
First published October 7, 2026. Last reviewed October 7, 2026. Spot an error? Tell us and we will check it against the source.