Usually when there is a sewer backup there are warning signs: strange flush, unusual sounds, and perhaps some sewage slowly coming up the shower.
But the real horrors start when you have plumbing in the basement and sewage starts flowing down there from a sewer backup. It might be a while until you notice.
Three safety measures help us mitigate the damage and let us respond in time to fix the issue:
Additional float in the pit that sounds an alarm, activates a light or sends a text message when the pit begins to overfill;
Check valve after the pump, this helps the pump cycle less and also prevents sewer backups from going downstairs;
That loop in the discharge pipe, the pipe is now higher than the lowest point on the main floor, so when there is a backup the sewage can't flow back through the discharge and travel downstairs.