Most houses with sump pumps rely on the pumps to keep the basement from flooding. When a big rain storm comes through, the sump pump will really be needed... and that's also the time that the power to a neighborhood is most likely going to get knocked out, disabling the sump pump and allowing the basement to flood. This happened to a lot of homes in North Minneapolis this spring after the tornado came through.
If your sump pump quits working, will you know about it before your basement floods? Do you have a backup in place? Does it work? Are you sure? If you depend on a sump pump to keep your basement from flooding, it's important to have a backup system in place, just like it's important to back up the hard drive on your computer.
It's one of those things that most people don't think about until it's too late. If you want to protect your basement from flooding, get a backup system. There are a few different backup systems available.
Secondary Electric Pump
A secondary electric pump would be a good option to keep your basement from flooding in the event that your primary sump pump failed. The secondary pump would need to be installed a little bit higher in the sump basket than the primary pump. The downside to installing one of these is that if the power to your house went out, the pump would be useless.
By far, the most common type of backup sump pump system that I've encountered is a battery powered system. This consists of a big heavy battery that's about the size and shape of a car battery, as well as a backup sump pump that sits in the sump basket a little bit higher than the primary pump. This system will save your basement from flooding if your sump pump fails or your power goes out.
The Basement Watchdog is a brand that makes backup batteries with a warning to tell you if the battery has a problem. This is a good feature to have, because I find that many backup batteries are dead.
If you already have a backup battery for your sump pump and it doesn't have a warning to tell you if the battery is dead, you should test it periodically. You can simply unplug your standard sump pump and fill the sump basket with water using a garden hose to test the backup pump.
Another backup option for your sump basket is to install a pump that is powered by the municipal water pressure coming in to your home. The nice thing about hydraulic pumps is that you don't have to worry about keeping a battery charged all the time, and if you have an extended power outage, you won't have to worry about the pump failing.
The downside to using a hydraulic sump pump is that they're not nearly as powerful; the video below shows just how slow they pump water. The original video was nearly three minutes long, so I cut out the middle as it got a little boring.
If the water at your home is supplied by a well, a hydraulic backup pump obviously wouldn't be any good, as a power outage would also knock out your well pump.
High Level Alarm
No matter what type of system you have installed, it's a good idea to have a high level alarm installed in your sump basket. These alarms will sound off if the water level in your sump basket gets too high, and you can buy one for under ten bucks at Home Depot. If you don't have a backup system in place, these alarms will at least tell you that you have a problem and you need to jump in to action.
I inspected a very nice home this year that had a completely finished basement that definitely could have benefited from one of these high level alarms. This house had in-floor ductwork; when the sump pump failed, the ducts ended up filling up with several inches of water. Click these links to see photos of the flooded ductwork and flooded ductwork 2.
The water level in the sump basket never got high enough for the basement floor to get wet, but the standing water in the ducts acted like the worlds largest whole-house humidifier, which caused major condensation throughout the basement; even the outlet covers were dripping with water. If the sump basket had been equipped with a cheap little high level alarm, this never would have happened.
If you want to have a backup sump pump professionally installed, hire a plumber to do it. Mark Jerde with RM Mechanical tells me that he has installed dozens of these systems.
Reuben Saltzman, Structure Tech Home Inspections