A sump pump that fails in a storm is the difference between a dry basement and a flooded one. Here's how to test, maintain, and know when to replace yours.
A sump pump sits in a pit in your basement floor and does one job: move groundwater away from your foundation before it reaches the floor. It's the thing standing between you and a flooded basement during a storm or a spring thaw — and it almost always fails at the worst possible time. A little quarterly maintenance goes a long way.
What the pump actually does
Groundwater collects around your foundation footings and drains (via weeping tile or a sump crock) into the sump pit. When the water rises to a set level, a float switch turns the pump on, and the pump pushes the water out through a discharge pipe to a safe spot away from the house. When it's working, the pit is dry and you never think about it.
Test it four times a year
The most common reason a sump pump fails is that it sat idle for months and the switch seized or the impeller jammed. A two-minute test every few months catches that:
- Lift the float manually. With the pump plugged in, lift the float arm (or pour a bucket of water into the pit until the float rises). The pump should turn on immediately and move the water out. If it doesn't fire, or it hums but doesn't pump, the switch or the impeller is the likely culprit.
- Listen to it run. A healthy pump runs smoothly and quietly. A grinding, rattling, or straining sound points to a worn bearing, a jammed impeller, or a motor on its way out.
- Check that the water actually leaves. Go outside to the discharge point and confirm water is flowing. If the pump runs but the pit doesn't drain, the discharge line is likely frozen, clogged, or kinked.
The discharge line
The discharge pipe carries pump water away from the foundation — and it's where a lot of failures happen. Make sure it exits at least two metres from the house and slopes away, so the water doesn't recycle back to the footing. In winter, a buried or low-slope discharge line can freeze solid; a small weep hole drilled in the pipe just above the pump connection lets trapped water drain so it doesn't freeze the line or burn out the pump against a frozen blockage. Never route the discharge into a floor drain or the municipal sewer — it's against code and it overwhelms the sewer in a storm.
The battery backup
A pump only works when the power is on — and the storms that flood basements are the same storms that knock out power. A battery-backup pump (or a water-powered backup) is the insurance that keeps your basement dry when the main pump can't run. Test the backup the same way you test the main: simulate a rise and confirm the backup fires. Check the battery every year — a backup with a dead battery is a false sense of security.
When to replace
Sump pumps last 7–10 years on average, and they tend to fail at the end of a storm rather than the start. If yours is older than that, runs noisily, cycles on and off frequently even in dry weather, or you've had to reset it more than once, it's time to replace it before it fails. We size the replacement to your pit and your discharge head (how high the water has to be lifted to exit) so it moves water fast enough to keep up with a real storm.
Don't forget the crock
The sump pit itself collects grit, sand, and debris that can jam the impeller. Once a year, unplug the pump, lift it out, and clean the debris from the crock and the pump intake screen. A clean crock keeps the pump running efficiently and extends its life.
If your basement is finished or in use as living space and the sump pump is your only defence against groundwater, a backup pump and an annual check aren't optional — they're cheap insurance against the single most expensive water damage a home can suffer. We install, test, and replace sump and backup systems, and we'll tell you honestly whether yours is keeping up.
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