My pump hums but does not pump. What is that?

A seized impeller or a stuck float. Unplug, clear debris, and retest. If the motor hums with no impeller motion even clear of debris, the pump is likely done.

How often should I test it?

At least twice a year — spring and fall are reasonable anchors, but before storm season in your region is the real one. Pour a bucket in and confirm it kicks on and clears.

Do I need a battery backup?

If the basement is finished, if storms knock out power in your area, or if water damage there would be expensive, yes. For an unfinished basement with cheap storage, a primary alone may be enough.

Why is my pump running constantly?

Usually a failed check valve sending discharged water back into the pit. Sometimes a high water table or a broken discharge line dumping water near the foundation.

How long do they last?

Primary pumps typically seven to ten years. Heavy use shortens that, and any pump past the ten-year mark is worth proactively replacing before failure.

Honest Advice

Sump pump not working: check these first

By Ken HovenUpdated April 20268 min read

A sump pump does nothing for months, then everything depends on it one afternoon. If there is any doubt about yours — a storm on the way, snow melting, a quiet basement in a wet season — test it now. Do not wait until the basin is filling.

Start with a quick sequence

Before any troubleshooting, run these four checks in order.

Is it plugged in? Sump pumps get unplugged for freezer access, basement reorganizing, or by accident. Check the cord first.
Is the outlet live? Sump pumps are usually on GFCI outlets. A tripped GFCI leaves the pump dead and silent. Reset and confirm. If the GFCI keeps tripping, that is the next problem to solve.
Lift the float or pour a bucket of water into the basin. A healthy pump kicks on within seconds.
If it runs but water does not leave, the problem is on the discharge side, not the pump itself.

Those four steps catch a surprising share of "dead" pumps before you even pick up a tool.

Why sump pumps actually fail

The float switch is stuck. Debris in the basin, a tether wrapped on the wall, or a worn float. The motor cannot start because the switch never signals. This is the most common failure by a wide margin.

The check valve failed. The one-way valve on the discharge pipe stops water from running back into the basin after each cycle. When it fails, water returns and the pump runs constantly without making progress.

The discharge line is clogged or frozen. Mud, debris, or winter ice. The pump runs, nothing leaves.

Motor or impeller failure. A burnt smell, a hot housing, humming with no flow, or complete silence when the float is raised. That is end-of-life.

Float switch — the quick fix

Unplug the pump. Pull it out of the basin (gloves — that water is not clean). Inspect the float. A tethered float should move freely; a vertical float's rod should slide without binding. Clear debris from the basin bottom. Reinstall and retest with a bucket of water. Many pumps declared dead come back after five minutes of float cleaning.

Check valve and discharge

With the pump unplugged, look at the vertical discharge pipe. The check valve is usually an inline fitting one to two feet above the pump. A failed check valve is inexpensive — often $15 to $30 for the part — and replaceable with a pair of pipe wrenches and a few minutes if unions are present.

On freezing days, walk outside and look at where the discharge exits the house. A frozen or buried discharge will back water up and can shut the pump down or kill it. A freeze-guard fitting or pop-off adapter near the exit helps.

Motor and impeller

If the motor hums when the float raises but nothing moves, the impeller may be seized with debris — sometimes freeable with a gentle manual turn (pump unplugged) — or the motor is burnt out. A pump that is running constantly, hot to the touch, or smells burnt is telling you plainly that it is failing. Do not ride it through the next storm. Replace it.

DIY replacement vs. hiring

Replacing a sump pump is within reach for a moderately handy homeowner. The sequence: shut off the breaker, disconnect the discharge (hopefully at a union fitting — if there is no union, there is cutting and reconnecting involved), lift the old pump out, drop the new one in, reconnect, reset the breaker, and test with a bucket of water.

The pitfalls worth knowing before you commit:

Mismatched discharge pipe diameter between old and new pump.
A basin too narrow for the replacement's footprint.
A pump undersized for the home's actual water volume.
A primary-only system in a house that really needs a battery backup.

A word on backup and power outages

A primary pump is single-point protection, and it fails exactly when the power fails — which is exactly when you need it. A sump pump battery backup runs off a deep-cycle battery and kicks in when the primary fails or the power drops. A water-powered backup uses municipal water pressure and needs no battery, only adequate pressure and a plumbing connection.

If the basement is finished, stores anything valuable, or the neighborhood loses power during storms, a backup adds real resilience. On the first storm it handles, it tends to pay for itself. If water does reach the walls, our drywall damage after a leak guide covers the dry-and-inspect sequence.

Rough cost ranges

DIY pump replacement: pump often $150 to $400, plus check valve and possibly a new fitting.
Professional pump replacement: often $500 to $1,000 installed.
Battery backup system: often $400 to $900 for the unit plus install.
Water-powered backup: often $300 to $600 plus install.
Pit cleaning or discharge repair: often $200 to $500.

Lifespan

Primary sump pumps typically last seven to ten years. Heavy-use pumps fail sooner. If yours is in that window, especially if it has been running hard through recent wet seasons, plan the replacement before failure rather than after.

Sources

Frequently asked

My pump hums but does not pump. What is that?: A seized impeller or a stuck float. Unplug, clear debris, and retest. If the motor hums with no impeller motion even clear of debris, the pump is likely done.
How often should I test it?: At least twice a year — spring and fall are reasonable anchors, but before storm season in your region is the real one. Pour a bucket in and confirm it kicks on and clears.
Do I need a battery backup?: If the basement is finished, if storms knock out power in your area, or if water damage there would be expensive, yes. For an unfinished basement with cheap storage, a primary alone may be enough.
Why is my pump running constantly?: Usually a failed check valve sending discharged water back into the pit. Sometimes a high water table or a broken discharge line dumping water near the foundation.
How long do they last?: Primary pumps typically seven to ten years. Heavy use shortens that, and any pump past the ten-year mark is worth proactively replacing before failure.

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