Sump Pump Not Working? Common Problems and What to Check

A sump pump only matters on the worst day of the year, the heavy storm or the spring melt when groundwater rises fast. That is exactly when a failure turns into a flooded basement. The frustrating part is that most sump pump failures give warning signs first. If you know what to listen and look for, you can catch the problem before the water does.

The pump will not turn on

A pump that stays silent while the pit fills is the most urgent failure. Run through the basics first:

• Confirm it is plugged in and the outlet has power. A tripped breaker or a bumped plug is a common and harmless cause.
• Check the float. If the float that triggers the pump is stuck against the pit wall or jammed by debris, the pump never gets the signal to start.
• Lift the float by hand. If the pump runs when you raise the float, the switch or the float is the issue. If nothing happens, the motor or wiring may have failed.

If the pump is dead with power confirmed and the float free, it usually needs to be repaired or replaced. Because this is the failure that floods basements, it is worth treating as urgent.

The pump runs nonstop

A pump that never shuts off is wearing itself out and signalling another problem. Common causes include a float stuck in the on position, a discharge line that is blocked or frozen so the water keeps draining back into the pit, a pump that is undersized for the amount of water coming in, or a check valve that has failed and lets water flow backward after each cycle. Constant running burns out the motor, so it should not be left for long.

The check valve and the backflow problem

The check valve on the discharge line stops pumped water from draining back down once the pump stops. When it fails, the pump lifts the same water again and again. Replacing a worn check valve is a small job that often cures a pump that seems to cycle far too often.

Strange noises or vibration

Sump pumps are not silent, but new sounds mean something. Loud rattling can be a loose or damaged impeller. Grinding can mean worn bearings or debris in the pump. Gurgling after the cycle is often the check valve. None of these are emergencies on their own, but they tell you the pump is heading toward a failure, which is the time to have it looked at rather than after it quits.

Old age and no backup

Sump pumps do not last forever, and an aging pump is more likely to choose the worst moment to fail. If yours is getting on in years, runs rough, or has no backup for a power outage, it is worth planning a replacement before the next big storm rather than after. A battery backup is worth considering too, since the heaviest storms are also when the power tends to go out. This is the core of how we approach sump pump installation and replacement in Markham.

A sump pump is also only one part of basement flood protection. If sewer backups are a concern in your area, a backwater valve guards against a different threat, and the two work together. If water is already coming in, our emergency plumbing page is the place to start.

What it costs

A small fix like a check valve or float switch is inexpensive. A full pump replacement costs more, and adding a battery backup adds to that. We look at your pit, your pump, and how much water it has to move, then give you the price before any work begins. For broader pricing context, our blog on sump pump installation cost in Ontario breaks it down.

Frequently asked questions

Why is my sump pump not turning on when the pit is full?

The usual causes are lost power, a tripped breaker, or a stuck float that never signals the pump to start. If power is confirmed and lifting the float by hand does nothing, the pump itself has likely failed and needs attention quickly.

Why does my sump pump run constantly?

Constant running points to a stuck float, a blocked or frozen discharge line, a failed check valve letting water flow back, or a pump too small for the water coming in. It wears the motor out fast, so it should not be ignored.

How long do sump pumps last?

It varies with use and quality, but pumps do wear out. If yours is older, runs rough, or has survived several heavy seasons, plan a replacement before a failure rather than after a flood.

Do I need a battery backup for my sump pump?

It is worth strong consideration, because the worst storms often knock out power at the same time the pump is needed most. A backup keeps the pit clear through an outage.

Is a failing sump pump an emergency?

If the pit is filling and the pump will not run, yes, because a basement can flood quickly. If the pump still works but is noisy or aging, it is a warning to act soon rather than an immediate emergency.

Sump pump acting up before the next storm? MBM Plumbing checks the pump, the float, and the discharge line, tells you whether it needs a repair or a replacement, and quotes the price before any work starts. Serving Markham and the surrounding area.

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