Battery Backup Sump Pumps

Why backups matter

A primary pump can fail three ways: the power goes out, the pump wears out, or the float sticks. Any of those, during a heavy rain or spring melt, can put water on a finished floor within hours. A secondary pump with its own float and its own power source covers all three. In neighbourhoods with high water tables, such as parts of south Aurora and Bayview Wellington, we see it as part of a complete sump setup rather than an extra.

Battery versus water-powered

A battery backup uses a 12-volt pump mounted in the same pit, slightly above the primary, with a deep-cycle battery and charger on a shelf beside it. It runs for hours on a charge, depending on battery size and how often it cycles.

A water-powered backup uses municipal water pressure to create suction and pull water out of the pit. It needs no battery and runs as long as city water flows, but it uses a lot of water and requires a proper backflow preventer on the supply. It does not suit homes on private wells, because the well pump stops when the power does.

Battery care

Sealed maintenance-free batteries need little attention; flooded batteries need distilled water topped up a few times a year. Either type should be replaced every few years, before it fades. Write the install date on the case with a marker. The charger should show a healthy status light, and the shelf should keep the battery off the floor and clear of splashing.

Alarms and testing

Most backup systems include an alarm that sounds when the backup runs or the battery is low. Test the backup separately: unplug the primary, add water to the pit and confirm the backup pump starts and clears it. Plug the primary back in afterward. A quick test each season catches a dead battery while the weather is still dry.