A sump pump sits in a pit at the lowest point of a basement and pumps out groundwater before it can flood the floor. In areas with high water tables or heavy rain, it's the last line of defence against a wet basement.
How it works
Water collects in the sump pit through the perimeter drainage. When it reaches a set level, a float switch turns the pump on and it discharges the water outside, well away from the foundation.
Test it regularly
Pour a bucket of water into the pit to confirm the float rises and the pump kicks on and drains. Do this a few times a year and before the wet season. Clean debris from the pit and check that the discharge line isn't frozen or blocked.
Consider a backup
A sump pump fails exactly when you need it most — during a storm that knocks out power. A battery backup pump or a water-powered backup keeps pumping during outages and is cheap insurance against a flooded basement.