6 Reasons Your Sump Pump Runs Constantly, Fixes for Canadian Homeowners
6 Reasons Your Sump Pump Runs Constantly, Fixes for Canadian Homeowners
A sump pump that runs constantly is usually telling you one of five things: the float switch is stuck, the check valve has failed, the discharge line is clogged or frozen, inflow is simply too heavy for the pump’s capacity, or there’s an electrical fault. Before touching anything, cut power to the unit and note how long and how often it runs. Some of these fixes are safe to try yourself; others call for a licensed plumber.
TL;DR:
A pump that restarts every 20 to 30 seconds often has a failed or missing check valve, because discharged water drains back into the pit.
Pour water into the pit, time two full cycles, and record sounds and water changes; avoid dry running beyond a few seconds.
Long, steady runs during heavy rain can reflect genuine inflow, but the same pattern on dry days may mean the pump lacks capacity.
Stop and call a licensed electrician or plumber for a warm outlet, burning smell, or repeated breaker trips; do not repeatedly reset a tripping GFCI.
Clean the inlet screen and pit floor twice yearly, test the float monthly in wet seasons, and replace the tether switch every two years.
Table of Contents
Common causes and how to fix them
Most continuous-run complaints trace back to one of five problems. Here’s how to tell them apart and what you can safely do about each one.
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Float switch stuck or failed. The float can snag on the pit wall, discharge pipe, or debris, which keeps the switch in the “on” position even after the water level drops. Unplug the pump, lift the float by hand, and check that it swings freely; if it’s tangled, reposition the piping or clear the obstruction. Wayne Pumps notes that float switches are the most common field failure and recommends replacing the tether switch every two years as routine maintenance.
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Failed or missing check valve. If you hear the pump kick on every 20 to 30 seconds, water is likely draining back into the pit after each cycle and triggering the float again. InspectApedia identifies this short-cycling pattern as a classic sign of a bad or absent check valve on the discharge line, and the fix is a valve replacement rather than a pump replacement.
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Clogged, frozen, or kinked discharge line. A pump that strains and runs without actually moving water may be pushing against a blockage. In winter, check the exterior discharge point for ice buildup, and year-round, inspect for kinks in unsecured flexible hose, which tends to collapse or abrade over time.
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Heavy groundwater or an undersized pump. A pump running in long, steady stretches during heavy rain is often just keeping pace with real inflow. If that pattern continues on dry days, your pump may be too small for the job, and the fix is a higher-capacity unit or a second pump working alongside it.
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Electrical faults. A GFCI outlet that trips repeatedly, a circuit shared with other high-draw appliances, or low voltage from a loose connection can all cause erratic cycling. Don’t reset a tripping GFCI more than once without investigating. If you smell anything electrical or notice warmth at the outlet, stop and call a licensed electrician.
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Mechanical wear. A grinding, whining, or rattling motor usually signals worn bearings or a failing impeller rather than something you can lubricate or adjust. At that point, repair rarely makes financial sense next to a replacement.
Pro Tip: Keep a simple log of run times and sounds for a week before calling anyone. It turns a vague complaint into a diagnosis a plumber can act on immediately.
Short cycling and continuous running wear down a pump through different paths. Short cycling burns through switch contacts and motor starts, while long continuous runs overheat the motor and wear bearings faster than intended. Either pattern shortens the pump’s working life well below what it should deliver.
How to test your sump pump safely
Testing before you call a plumber saves time and often narrows the problem to a single part. Follow these steps in order, and keep your hands away from the pit water if you’re unsure about the wiring.
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Shut off power at the outlet and confirm the GFCI resets cleanly before restoring power.
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Pour water into the pit slowly to simulate real inflow, then watch for the pump to start, run, and shut off cleanly.
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Time at least two full on/off cycles and write down the seconds for each.
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Try the piggyback plug test recommended by Pentair: unplug the float switch’s piggyback connector and plug the pump directly into the outlet to see if the motor runs on its own, which isolates a float problem from a motor problem. Don’t let the motor run dry for more than a few seconds during this test.
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Record smells, noises, and how fast the water level drops for your plumber.
A continuous run of about half a minute between cycles usually points to a check valve problem, according to NDSU Extension, which also recommends the repeated fill-cycle test to confirm normal operation.
Preventive maintenance and upgrade options
A few habits keep most sump pumps out of the “runs constantly” category altogether.
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Inspect and clean the inlet screen and pit floor each spring and fall, since debris buildup is a leading cause of float snags.
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Test the float by hand monthly during wet seasons, and replace the tether switch every two years as Wayne Pumps recommends, even if it still seems to work.
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Confirm a check valve is installed on the discharge line and that the piping is rigid and secured, since unsecured flexible hose abrades and leaks over time.
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Add a battery backup pump or a second pump in a duplex setup for properties where a power outage during a storm would cause real damage.
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Install a high-water alarm as a low-cost early warning if the primary pump ever falls behind.
Pro Tip: Don’t treat thermal shutoff as a feature you can rely on. It’s an emergency safeguard that protects the motor from one overheating event, not a substitute for a pump sized correctly for your pit.
Before winter, clear the discharge line of any standing water that could freeze and block flow, and route the outlet so water drains well away from the foundation instead of pooling and refreezing near the exit point.
When to call a professional
Some symptoms aren’t worth troubleshooting further on your own.
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An electrical smell, warm outlet, or repeated breaker trips mean stop and call a licensed electrician or plumber right away.
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A motor that cycles its thermal protection more than once in a short period is signaling overload, not a one-time fluke.
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A pump that runs but moves no visible water usually means a seized impeller or a fully blocked line.
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Grinding or whining from the motor housing usually means the unit is near the end of its working life.
When you do call, have your run-time log ready: how long each cycle lasts, how often it repeats, what you’ve already tested, the pump’s age, and whether it’s seen a freeze event this winter. That information lets a plumber arrive with the right parts rather than guessing on site. We quote jobs on-site and waive the call-out fee when the repair goes ahead.
Why an owner-led plumbing team matters here
We have extensive experience in the trade, and the owner is the one who shows up to diagnose your pump, not a dispatched stranger. We offer 24/7 emergency plumbing, drain cleaning, and sump pump repair and installation work across the properties we serve, and we have excellent customer reviews. That track record comes from being the technician on every job, not just the name on the invoice.
What homeowners get wrong about sump pump troubleshooting
Most advice on this topic treats every continuous-run pump as a replacement job, and that’s where homeowners waste money. A stuck float or a failing check valve costs a fraction of a new unit, and both are easy to rule in or out with a bucket test before anyone reaches for a credit card.
The bigger blind spot is treating thermal shutoff as normal behavior instead of a warning. A pump that trips its thermal protection once in a while isn’t “handling it fine.” It’s telling you something upstream (a clog, a stuck float, an undersized unit) is forcing it to work harder than it should, and ignoring that pattern is how a $30 switch replacement turns into a $400 motor failure.
If you take one thing from this guide, let it be the run-time log. Five minutes with a stopwatch tells you more than guessing ever will, and it’s the single detail that turns a frustrating repair call into a fast, accurate one.
— Jon
Get an honest fix for a sump pump that won’t shut off
When a sump pump runs nonstop during a storm, waiting for a callback isn’t really an option. Our 24/7 line puts you in touch with the person who actually does the work, and we quote the repair on-site before anything gets replaced.
Have your run-time log ready when you call: how long each cycle lasts, how often it repeats, and whatever you’ve already tested with the float or breaker. Reach out through our Emergency Plumbing page any time, day or night, and we’ll get someone out to look at it.
FAQ
How do I fix a sump pump that keeps running?
Start by unplugging the pump and checking the float switch for snags, then inspect the check valve and discharge line for blockages. If the float moves freely and the line is clear, the problem is likely an undersized pump for your inflow or an electrical fault, both of which are worth a professional diagnosis.
Is it normal for my sump pump to run every 30 seconds during rain?
Cycling every 30 seconds usually points to a failed or missing check valve rather than normal heavy inflow, since water is draining back into the pit and re-triggering the float. InspectApedia describes this short-cycle pattern as a common sign the check valve needs replacing.
How long can a sump pump run continuously before it burns out?
There’s no fixed safe duration because it depends on the motor and how hard it’s working, but manufacturers build in thermal protection that shuts the motor down if it overheats and resets after it cools. NDSU Extension notes that relying on this thermal cutout as a normal operating pattern will shorten the pump’s life rather than protect it.
Is it normal for my sump pump to run every minute?
Running roughly once a minute can be normal during heavy, steady rain if the water level drops fully between cycles and the pump keeps pace. If that pattern continues on dry days with no rain to explain it, it usually means a stuck float, a check valve issue, or a pump that’s undersized for the property.