The primary pump works. The question is what happens on the evening when the rain is heavy and the lights go out together.
Define what the backup is meant to cover
Ask the installer which failures the proposal addresses: loss of mains power, failure of the primary pump, or another specific condition. Those are not automatically the same scenario.
Toronto's sump guidance notes the risk of power loss in storms and suggests considering battery backup. It does not establish the size or runtime for your house. That requires the actual equipment and pumping conditions.
Compare a system, not a battery label
Request the backup pump's performance at the intended discharge arrangement, the battery requirements, and the assumptions behind any runtime estimate. Ask whether that number means continuous pumping or intermittent cycles, and what water demand it assumes. The installer should also explain the testing and maintenance procedure. Put those answers beside the equipment model in the house records; an impressive number without its conditions is difficult to use when the weather turns.
Check the route and the warning
- Where does each pump discharge, and can that route remain clear?
- What happens if the primary pump fails while power is still available?
- How will an alarm be noticed, including when nobody is downstairs?
- Who will perform the scheduled checks and eventual battery replacement?
Keep the equipment accessible after finishing. A backup that cannot be inspected conveniently tends to become a forgotten purchase.
At handover, have the installer demonstrate the checks you're expected to make and how you'll know something needs attention. Save the equipment details and maintenance schedule where you'll find them during an outage. That's when a clear plan becomes more useful than the battery's biggest advertised number.