Why Sump Pumps Always Seem to Fail During Storms

By Mark Soto

July 24, 2025

Sump pumps are supposed to prevent your basement from flooding, but they can sometimes fail when you need them the most: during severe storms. Standing water in the basement after heavy rains can lead to expensive damage like mold growth and repairs you want to avoid. Stay prepared by ensuring your sump pump is ready for the worst-case scenarios.

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Troubleshooting: Why Sump Pumps Fail at the Worst Times

You rarely ever worry about sump pumps except when they need to perform their main function.

It’s easy for sump pumps to remain almost invisible in the background and when you completely ignore them, it can cause failures. Like all systems and appliances in your home, sump pumps require routine maintenance. If you aren’t keeping up with your sump pump maintenance, it’s hard for the pump to work at its full capacity when it needs to.

Cause #1: Power Outages

One of the most common reasons why sump pumps fail is due to power outages. Since heavy rainstorms can cause the power to go out, lacking a battery backup pump means you won’t have any protection against flooding. You can buy a battery backup sump pump system that features a sump pump along with a second battery backup pump that activates when the first one fails. You can also purchase a single battery backup sump pump and pair it with your existing one.

Cause #2: The Discharge Pipe Is Backing Up

The sump pump is supposed to push water away from your home through a discharge pipe. However, the discharge pipe can get clogged with debris like dirt, leaves, rocks and other things that impede the water flow. When the water can’t escape, it can seep back down into your basement, causing the pump to overheat and shut down due to non-stop work. Homeowners should routinely inspect and clean the discharge pipe to remove any debris inside. You can also install a drain cover to help prevent clogging.

Cause #3: The Float Switch Isn't Working

The float switch is responsible for informing your sump pump to turn on when the water rises to a certain level. There are times when the float switch can get stuck and prevent it from rising when debris is in the way, it gets caught on the basin or the mechanism breaks down due to wear and tear. That’s why it’s essential to test your sump pump float switch before the rainy season arrives. An easy test is to simply fill the sump pump with water and verify that the float switch correctly moves upward and causes the sump pump motor to start up.

Signs Your Sump Pump Might Fail

Once your sump pump starts to make strange noises, that’s often a telltale sign that something is wrong with it. Normal noises like low humming are common, but other than that, it shouldn’t be making any additional noise. Different noises can come from a damaged motor or impeller.

Like any appliance or system in your home, old age can eventually catch up to your sump pump and the years of wear and tear will eventually cause it to fail. Most sump pumps have a lifespan of around 10 years, so if it’s been longer than that since you last replaced it, then it’s time to consider buying a new one. Remember to invest in a sump pump with a backup system so you’re protected if the main one fails.

If there are visible signs of rust on various areas of the pump, you should consider purchasing a new one. Since it's always coming into contact with water, light rust is to be expected. But it becomes a problem when essential components like the impeller or motor area have significant amounts of it. Rust can cause your sump pump motor to overheat and fail eventually.

Excessive vibrating when in use can signal that the impeller is either loose or bent. While tightening it might solve the problem, if the impeller is dented, it might require replacement. The check valve might also be faulty, so replacing it can sometimes resolve the vibration problem.

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How Can You Prevent Sump Pump Failure?

The best way to prevent sump pump failure is by keeping up with your maintenance and yearly testing. Maintenance can include cleaning the discharge pipe and removing any debris to prevent clogs ahead of time. You should also be cleaning the pump on a quarterly basis. Unplug the pump, open the lid and clean the sump pit by removing any dirt, sand, mud or other debris.

You should run a yearly test to ensure the sump pump works properly before a rainstorm. This test can help determine whether parts of your sump pump need repairs or you need a whole new unit. Pour water in the sump pump and verify that the float switch activates the pump once it reaches its specific level.

There are also professionals who are trained to inspect sump pumps and who know exactly what to look at. Consider calling a sump pump contractor and getting an inspection. It might end up saving you a significant amount of money and headaches if it ends up preventing your basement from flooding.

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