Sump Pump Not Turning On: Troubleshooting
A sump pump not turning on is one of the most urgent plumbing problems a homeowner can face, because the pump is your basement's last line of defense and every hour it sits dead is an hour closer to a flood. Before you panic or pay for a replacement, work through the causes in order, because most dead pumps turn out to have a simple problem: a tripped breaker, a loose plug, a stuck float, or a clogged impeller. This guide follows the same order a technician would, starting with the free five-minute checks and moving toward motor and electrical faults that need a professional. Keep the pump area dry, never reach into standing water near an electrical outlet, and if water is already rising fast, skip straight to the emergency steps near the end of this guide.
First: Check Power Before Anything Else
It sounds obvious, but power problems are the single most common reason a sump pump appears dead, and they are also the easiest to miss. Sump pumps should be on a dedicated circuit, and many are plugged into a GFCI outlet that can trip after a power surge, a storm, or a small ground fault. Go to the outlet first: press the reset button on the GFCI, confirm the plug is fully seated, and check whether anything else on that circuit has lost power. If the outlet is dead, check your breaker panel for a tripped breaker and reset it once. If it trips again immediately, stop resetting it and call an electrician, because a breaker that trips repeatedly is protecting you from a short circuit or a ground fault in the pump or its wiring.
The Float Switch Is the Usual Suspect
The float switch is the component that tells the pump when to run, and it fails more often than the motor itself. Lift the float by hand with the pump plugged in. If the pump starts, the switch works and the problem is that the float is not rising on its own, usually because it is tangled, jammed, or set too high. Tethered floats swing on a cord and can snag on the discharge pipe, the power cord, or the pit wall. Vertical floats slide on a rod and can stick on mineral scale, rust, or silt. Clear the obstruction, reroute cords away from the float's path, and clean the rod or pivot with a brush. Then pour water into the pit and confirm the pump turns on and off at sensible levels.
If lifting the float does nothing, the switch itself may be dead. Float switches wear out, fill with water, or corrode at their electrical connections, especially in pits with hard or iron-rich water. Replacement switches cost $25 to $60 for most common brands, and on many pumps the switch is a plug-in module that swaps out without tools. Before buying one, confirm your pump model and switch type, because tethered, vertical, and electronic sensor switches are not interchangeable. Some newer pumps use electronic water sensors instead of a mechanical float; if yours does, clean the sensor probes, since a film of minerals or biofilm can insulate them and prevent detection. A float that is set too high is a subtler problem: the water may rise above the floor drain or seep through the wall joint before it ever reaches the trigger level, so check the manual for the correct on and off heights and adjust accordingly.
Clogs, Jams, and a Stuck Impeller
If the pump hums, buzzes, or clicks when the float is lifted but does not pump, the motor is getting power and the impeller is likely jammed. Unplug the pump before touching it, then lift it out of the pit and inspect the intake screen and impeller housing. Sump pits collect silt, small stones, toys, and debris that wash in through the drain tile, and any of it can block the intake or wedge the impeller. Clear the screen, remove visible debris, and try spinning the impeller by hand if your model allows access; it should turn freely. A pump that sat unused all winter can also seize from corrosion or mineral buildup, and sometimes working the impeller free by hand restores it. If the impeller is cracked, melted, or missing blades, it needs replacement, and on many budget pumps the cost of parts and labor approaches the price of a new unit.
Also check the discharge line. A pump can appear dead if it is trying to push against a frozen, crushed, or fully clogged discharge pipe, though this usually shows up as a humming motor or a pump that runs briefly and then trips its internal overload. In cold weather, ice at the outdoor outlet is a prime suspect; clear it and check the line for a low spot where water pools and freezes. Inside, disconnect the discharge pipe above the check valve if you are comfortable doing so, and see whether the pump runs freely into a bucket. That test separates a pump problem from a pipe problem in minutes. A check valve installed backward or stuck shut will also block flow completely, so confirm the arrow on the valve body points away from the pump. For routine cleaning steps that prevent these jams, see our sump pump maintenance guide.
Motor and Electrical Problems
When power, float, and impeller all check out, the motor itself is the remaining suspect. Signs of motor failure include complete silence with good power and a working switch, a burning smell, a motor that is hot to the touch after a short run attempt, or a breaker that trips the instant the pump tries to start. Most sump pump motors have a built-in thermal overload that shuts the motor down when it overheats; if yours tripped, let it cool for 30 to 60 minutes, clear any jam, and try again once. Repeated overload trips mean the motor is failing or the pump is undersized for the head height it must push against, and continued attempts will only shorten its remaining life.
What to Do While the Pump Is Down
A dead pump during dry weather is an inconvenience; a dead pump during a storm is an emergency. If water is rising in the pit, act immediately. A portable utility pump, available at most hardware stores for $80 to $200, can be dropped into the pit and run with a garden hose to the outside as a temporary stand-in. A wet-dry vacuum helps for shallow water, and moving valuables, boxes, and electronics off the basement floor buys time. If you have a battery backup pump, it may already be running, but check its battery, since backups that have never been tested often fail when they are needed most. Keep the main pump unplugged while you work around the pit to avoid a shock hazard, and never stand in water while handling a plugged-in electrical device.
Watch the weather forecast while the pump is down. If heavy rain is expected before a repair can be completed, consider renting a larger portable pump or asking a plumber about emergency service. Document the water level with photos, because that record is useful for an insurance claim if flooding does occur. Once the immediate threat passes, use the downtime to improve the system: clean the pit thoroughly, replace a questionable float switch, and consider adding a water alarm that alerts you the next time the pump fails silently. Many pump failures go unnoticed for weeks because nobody checks the pit, and a $15 to $40 alarm is the cheapest insurance against that. If constant running rather than silence is your problem, our guide to a sump pump running constantly covers that side of the coin, and the sump pumps hub collects all of these guides.
When Replacement Beats Repair
Replace rather than repair when the pump is old, the motor is dead, or repair costs approach half the price of a new unit. A new submersible sump pump costs $150 to $400 for the unit, and professional installation including labor typically brings the total to $500 to $1,500, depending on whether the basin, check valve, or discharge line also needs work. That price buys a new warranty, a more efficient motor, and often a better switch design than the one that failed. If your old pump struggled to keep up even when it worked, this is also the moment to reassess sizing, because replacing a 1/3 HP pump with another 1/3 HP pump repeats the original mistake. Our sump pump size guide explains how to match horsepower to your home, and our sump pump installation cost guide breaks down 2026 pricing in detail.
Consider adding a backup system at replacement time rather than later. A battery backup pump costs $300 to $800 installed and covers power outages, while a water-powered backup uses municipal water pressure and needs no battery but requires adequate city water pressure to work. A dual-pump setup, with a primary and a backup in the same pit, is the most robust option for finished basements or homes with a history of flooding. Whichever route you choose, test the new pump before the installer leaves: pour water into the pit, watch it cycle on and off, check the discharge outside, and confirm the check valve prevents backflow. Write down the model number, installation date, and warranty terms, and set a calendar reminder to test the pump quarterly. A pump that is tested regularly rarely fails without warning.
FAQs
Why is my sump pump not turning on at all? The most common reasons are a tripped GFCI or breaker, a loose plug, a stuck or failed float switch, a jammed impeller, or a dead motor. Check power first, then lift the float by hand, then inspect for clogs.
How do I know if my sump pump float switch is bad? If power is good but lifting the float does not start the pump, the switch is likely bad. If the pump starts when you lift the float but not on its own, the float is probably tangled, jammed, or set too high.
Can I reset a sump pump? Yes. Unplug it, wait a minute, and plug it back in. If it has a thermal overload, let the motor cool for 30 to 60 minutes first. A pump that repeatedly needs resetting has a deeper problem that should be diagnosed.
How long do sump pumps last? Most last 7 to 10 years with regular maintenance. Pumps in high-water-table homes or pits with heavy silt may wear out sooner, while lightly used pumps can last longer.
What should I do if my sump pump dies during a storm? Use a portable utility pump in the pit as a temporary stand-in, move valuables off the floor, and call a plumber for emergency service. Do not stand in water while handling plugged-in electrical equipment.