How to test a sump pump

Failed sump pumps lead to flooded basements. While it’s important to have a backup plan in place for a failed sump pump, it’s also a good idea to test your sump pump in the spring. Today I’ll show you how.

You need access

Most sump baskets have a plastic removable cover, often held in place with a few drywall screws. That’s what I have at my own house, and it looks like this:

Sump cover lid

To open this, I just need to back out the screws and give the cover a hard yank.

Removing sump cover

A few very lucky people have fancy covers like this one. Clear top, hinges, gasket, thumb screws… be still my heart.

Fancy Sump Cover

On the other end of the spectrum, most new construction houses have covers that are gooped shut with caulk.

Sump cover caulked shut

You can’t open that thing without busting a bunch of utility knife blades trying to cut through all the caulk. Our Radon Code requires sump baskets to be sealed to prevent radon gas from entering the home, and this is the quick and dirty way to do it.

Testing the pump

The best way to ensure the full functionality of your sump pump is to simply add water to the sump basket. You can run a garden hose into the room, or you can carry buckets of water into the room and fill it that way. But I’ll warn you, it takes more buckets than you think.

Garden hose into sump basket

The reason this is the best method is because you’re not only testing the functionality of the pump, but you’re also making sure the float is functioning properly. The vast majority of sump pumps are activated by a float; when the water level gets high enough, the float tells the pump to turn on. If your float is obstructed by something or stuck in the bottom of the pit, you might not know about it unless you test your sump basket by adding water.

If you want to test your sump pump the easy way, just lift up the float. It’ll probably be a black floating valve about the size of a tennis ball, tethered to a cord. When you lift it up, your sump pump should kick on. When you drop it back down, your sump pump will turn off.

Lifting sump pump float

Some sump pumps have a float attached to the pump, and those work the same way. Lift the float to turn it on, drop the float and the pump should turn off.

And to make it especially easy to test a sump pump, you’ll often have two cords plugged into an outlet. The first is for the float, and the second is for the pump. The float controls the power to the pump as needed. To bypass the float, you can unplug both and then just plug in your pump.

Sump pump float plug

This is handy for those sump baskets with lids that are gooped shut.

What if it fails?

If your pump doesn’t activate, check the obvious stuff first. Is it plugged in? Is there power to the outlet? Do you have a failed float mechanism? Is the float stuck? Does the pump work if you plug it directly into an outlet? If you still can’t get the pump to turn on, it’s probably time for a new one. I consider sump pump replacement to be a very DIY type of project. If everything goes smoothly, you’ll spend more time driving back and forth to the store for a new pump than you will actually doing the work.

Written By

Reuben is a second-generation home inspector with a passion for his work. He grew up remodeling homes and learning about carpentry since he was old enough to hold a hammer. Reuben grew up thinking he was going to be a school teacher because he enjoyed teaching others so much. In a sense, that’s a lot of what home inspections are about, so Reuben truly does what he loves. Sharlene has worked with Structure Tech since 2000 and Reuben has been contributing to her blog since 2008.

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