Best Sump Pump Backup Systems of 2025
When your primary pump—or the power—fails, these top-rated models are ready to step in
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When the skies open and power lines go down, a reliable backup sump pump could be the difference between a dry basement and thousands of dollars in damage (along with a big headache). And because extreme weather events have increased in frequency, more homeowners are pulling off the cover of that mysterious basin in the corner of the basement and adding a backup sump pump, or replacing their old one.
Backup sump pumps automatically activate when your main sump pump fails—whether due to a power outage, a mechanical problem, or overwhelming water levels—ensuring that water removal doesn’t stop even when your primary system is compromised. These systems act as a fail-safe, stepping up to keep your basement dry.
- Best Backup Sump Pumps: Combo Battery Water-Powered
- How CR Tests Backup Sump Pumps
Power failures aren’t the only reason for a backup system. Sump pumps, which have an average life expectancy of a decade, can fail for other reasons. “Even if your power is on, sump pumps fail all the time because of age or lack of maintenance,” says Dave Jones, a master plumber with Roto-Rooter.
Find out whether a portable or a whole-house generator is right for your home.
Combo Backup Sump Pumps
Combo sump pump systems replace your existing sump pump with a setup that includes both a plug-in 120-volt primary pump and a battery-powered backup pump. These systems simplify installation, offering full protection without the need for separate units.
Some combo units sound an alarm when they switch from primary to backup; others sound an alarm only when the battery is low or depleted. These systems typically use a 12-volt deep-cycle marine battery, which is sold separately.
Both of CR’s recommended combo units come with a three-year warranty, typically covering the entire system, but it’s important to check specific warranty details for each model. Here are the top two we tested.
Battery Backup Sump Pumps
Battery-powered backup systems are a budget-friendly option, and if you’re comfortable with basic plumbing, you might even install one yourself.
These systems kick in when the water level rises above your main pump’s float switch, stepping up during power outages or when the primary pump fails. Like combo units, battery backup units typically require a 12-volt deep-cycle marine battery, which is sold separately. Most models can run for days on a single charge, giving you peace of mind through extended outages.
While they do need a separate discharge pipe and a bit more of an installation effort than combo units, they’re a solid choice for dependable protection. CR recommends these three models based on our tests.
Water-Powered Backup Sump Pumps
If you’re on municipal (not well) water, a water-powered unit could be a compelling backup option. In case of a power failure, these units kick on and use the force of the city water running through your pipes to create a suction effect to clear the sump basin.
Like battery backup systems, water-powered units are usually activated by a float switch that senses rising water levels when the main pump fails. These systems generally require lower maintenance and have longer lifetimes than battery backup units. But installation is more involved and requires a water supply line near the sump basin.
Like battery backups, these systems use their own discharge pipe, so your existing system’s plumbing will need to be modified. Here are the top two water-powered models from our tests.
How CR Tests Backup Sump Pumps
Our tests use rising water levels to recreate a main system failure. Flow rates are measured based on a 10-foot vertical lift, with each pump hooked up to a 10-foot vertical discharge pipe. Testers determine the flow rate by weighing a collection barrel before and after our tests to calculate gallons per minute.
For battery-powered units, each model is tested using a 12-volt deep cycle marine battery with a 75 amp-hour capacity. We measure the amperage draw during operation to provide insight into how long a fully charged battery can sustain the pump while working intermittently during a power outage.
Water-powered systems are tested using a similar setup: weighing a collection barrel before and after to track the amount of water pumped out. We also calculate the amount of municipal water it takes to pump each gallon out, providing a better picture of efficiency.
We also consider the installation required for each. Pumps that don’t need much fiddling with existing plumbing get higher marks, while systems that have more complicated setups—like water-powered ones—are rated accordingly.
Last, we consider material choices, noting the differences between cast-iron and thermoplastic models. And we detail features like alarms or WiFi connectivity that can tell you when your pump is active. While these extras don’t have a direct impact on performance, they can make a pump more user-friendly and provide a measure of reassurance that your system is up and running when you need it.
