Your Sump Pump Alarm Means the Main Pump Already Failed
Many sump pits contain two pumps, a main and a backup. If your alarm is sounding but there’s no water in the basement, that’s usually because the backup has taken over and the main pump is already dead. The alarm is not an early warning. It’s the last one you get before the basement floods.
Your sump pump alarm goes off. You go downstairs, you look in the pit, and there’s no water. So you shut the alarm up and get on with your day.
That is the single most expensive assumption a homeowner can make, and I only learned why because I had my own plumber on the podcast.
Zach is a licensed plumber and he’s been working on my house since 2023. He’s the guy I text on a Saturday night. I had him on Supply and Demand because the damage he saves people from is genuinely staggering, and almost none of it is complicated. It’s just stuff nobody ever explained.
This was the part that stopped me cold.
What is a sump pump, and why is it so easy to forget?
A sump pump sits in a pit in your basement floor. When groundwater rises up from the ground, the pump moves it out before it floods your basement. That’s the whole job.
“A sump pump is one of the easiest things to forget about in your home. It’s used very little. It’s only used as when the groundwater seeps up from the ground and floods your basement. It’s just there to keep it dry.”
How hard it works depends entirely on where your house sits.
Some pumps sit dry for years and barely run. Others run so constantly they need replacing twice a year. Same appliance, completely different life expectancy, and it comes down to groundwater. A house that has never had a drop in the basement can still be sitting on old marshland.
Because it does nothing most of the time, it’s invisible. Nobody thinks about the sump pump. That’s exactly the problem.
The backup pump nobody tells you about
Here’s the part that changes how you read the alarm. A lot of sump pits do not have one pump in them. They have two.
“Some pumps, like with yours, for instance, they have a backup system, right? And then the backup pump will go. Because there’s two little pumps sitting in your basement. You have your main sump pump and you have your backup pump.”
So the main pump dies. Usually the impeller, the moving part inside, disintegrates from the grit and stones sitting in the pit. The backup kicks in and starts doing the work. Your alarm sounds.
And this is where it goes wrong.
“But most people don’t understand there’s a backup pump in some of these pits. So they’ll keep going. And they’ll go. And they’ll go. And then the alarm will sound. And then you won’t see any water. And no water generally means no problem to most homeowners. Someone will silence the alarm.”
You look in the pit. It’s dry. Of course it’s dry. The backup pump is the reason it’s dry. The alarm is not telling you there’s water. It’s telling you your first line of defence is already gone and you are now running on your spare.
A dry pit with a screaming alarm is not a false alarm. It is the backup pump doing the job the main pump stopped doing. Silence the alarm and you’ve turned off the only thing that will tell you when the backup dies too. Zach: “And then all of a sudden you have a flooded basement.”
Zach’s number for what happens next:
“And when that fails, you’re looking at a $30,000 renovation sometimes.”
That’s his estimate from what he sees in the field, not a quote. But think about what’s actually down there. Finished basement, drywall, flooring, whatever you’re storing. Then mold on top of it.
How a silenced alarm becomes a flooded basement
The design flaw I found in my own sump pit
Zach came over to look at mine, opened it up, and the float was caught on the side wall.
Here’s how the float is supposed to work: water rises, the float rises with it, and when it gets high enough it switches the pump on. Simple. Except the inside walls of my pit were ridged, not smooth. So the float rides up, catches on a ridge, and just sits there. Water keeps rising. Pump never turns on.
“That is a serious design flaw in my mind. I think they should all be smooth. They should not have ridges in them just for that reason alone.”
If you are ever choosing a sump pit or having one replaced, smooth walls, every time. You are watching the mechanics fail on the ridged ones.
This is also part of a bigger point Zach kept coming back to: a lot of the equipment that causes these problems was bought online rather than from a plumbing supplier. Undersized parts, odd design choices, plastic where there should be brass. When he buys from a supplier, he gets parts that are to code, that he can get replacements for, and that carry a warranty.
What you should actually do about it
Go look in your pit. One pump or two? Now you know how to read your own alarm.
Never silence an alarm you haven’t diagnosed. A dry pit is not the all-clear. It may be the backup covering for a dead main pump.
Book it once a year with the rest of your mechanical systems.
If you travel or own a cottage, get an alarm that reaches your phone.
On the maintenance point, Zach knows it’s a tough sell right now:
“I know it’s not generally in the budget for most people nowadays. But a yearly maintenance with your mechanical systems in your homes is almost a necessity at this point. Because you’re saving yourself a huge headache and tens of thousands of dollars. And one ounce of prevention is a pound of cure.”
Can you get a sump pump alert on your phone?
Yes, and it’s the upgrade that made the most sense to me. Zach is installing one at my place. A sensor sits at floor level, and it pairs with an app.
“As soon as there’s a high water alarm or an alert, it immediately alerts you to your phone, anywhere in the world, wherever you are. As long as you’re connected to a signal, you have some data.”
It’s the same idea as the alarm already in your pit, just wireless and connected. There are a few brands. Zach’s preference is NightEye, which he says fails the least and has the best software. That’s his opinion from installing them, not a Vision endorsement, and there’s also an in-ground kit if you’re building new.
Be clear about what this does and doesn’t do. It does not stop your pump from failing. It just means you find out while you can still call someone, instead of finding out in February when you get back from a week away.
Why I think this matters more than it sounds
I sell houses in Toronto and York Region. Water is the thing that turns a manageable problem into a five-figure one, and the sump pump is the least glamorous appliance in the entire building. Nobody stages a sump pit. Nobody asks about it at a showing.
But this one is free to fix. Go look in the pit. Count the pumps. That’s it. If there are two, you now know that your alarm means something completely different than you thought it did this morning.
And if you’re buying, this belongs on the same list as everything else you can’t see. My conversation with a home inspector covers the rest of what hides behind the walls.
Frequently Asked Questions About Sump Pumps
My sump pump alarm is going off but there’s no water. Is that a problem?
Do I have a backup sump pump?
Why do sump pumps fail?
How often should a sump pump be serviced?
Can I get a sump pump alert on my phone?
Related Reading
- What a Home Inspector Actually Looks For, including what the decade your house was built predicts about its plumbing.
- Property Maintenance Checklists, the seasonal version of the yearly service Zach is describing.
- Renovations That Pay Off, worth reading before you finish a basement that sits over a sump pit.
Watch the Full Episode
This is from my conversation with Zach, a licensed plumber, on Supply and Demand. He also gets into the wet spot on my kitchen ceiling that turned out not to be a leak at all, and the $100,000 mistake he made himself before he was licensed. Listen on Apple Podcasts or Spotify.
If you’re buying or selling in Toronto or York Region and want to talk through what to look for, or you need a plumber who will tell you the truth about what you actually need, I’m happy to point you in the right direction.
Written by Adam Nadler, a licensed REALTOR serving Toronto and York Region with RE/MAX Your Community Realty, Brokerage. Nothing here is plumbing or building code advice. Costs and code requirements vary by municipality and change over time. Always hire a licensed technician.