Troubleshooting · Last updated August 1, 2026
Five real causes, roughly in order of how often they're actually the culprit — check these before assuming the whole unit needs replacing.
By far the most common cause, and the cruelest timing: outages tend to happen during the exact storms that fill the pit fastest. A sump pump is almost always a standard AC-powered appliance with zero inherent backup — if the breaker's fine and the pump still won't run, check whether the whole house actually has power before assuming the pump itself failed.
The float switch is what tells the pump when water has risen high enough to activate. If it gets wedged against the side of the pit, tangled in the power cord, or simply fails mechanically, the pump never gets the signal to turn on even though it's otherwise perfectly functional. This is one of the easiest fixes on this list — often just a matter of repositioning the float so it can move freely.
If the pump is running — you can hear the motor — but no water is actually leaving the pit, the discharge line itself may be blocked. Debris inside the pipe is one cause; in cold climates, the exterior end of the discharge line freezing shut in winter is a genuinely common one that has nothing to do with the pump's internal mechanics at all.
A pump rated for typical seepage can genuinely be outpaced by an unusually heavy storm or a rising water table it wasn't sized for. This shows up as a pump that's running constantly and still losing ground, rather than one that's silent and unresponsive — a different symptom pattern worth distinguishing from an outright failure.
Sump pumps typically last 7 to 10 years with normal use. Past that range, a pump that's simply stopped running — no clicking, no humming, nothing — is often just at the end of its mechanical life rather than something with a specific fixable cause. If the other four causes above don't explain what's happening, age is the most likely remaining explanation.
Since power outages are the single most common cause, pairing your primary pump with a battery backup system covers the failure mode that catches the most people off guard. A waterproof sensor in the pit adds an early warning for any of the other four causes too — if water's rising past where the primary pump should have already handled it, you'll know before the basement floods rather than after.
FAQ
Power outage — sump pumps are almost always AC-powered with no built-in backup, and outages often hit during the same storms filling the pit fastest.
Depends on the cause. A stuck float or clogged line, often yes. A burned-out motor or an undersized pump, usually means replacement.
A battery backup handles the outage scenario specifically; a pit sensor gives you an early warning for the other causes too.