I was going to recommend a backup pump as well. I went with a battery backup pump for a few reasons. First, if you lose water pressure, your backup pump won't work. Second, at least in my city, you need to have the backflow preventer inspected annually, and that was like $150/year or something crazy. The battery seems to work well. It's rated for around 8 hours, but that's continuous use. We lost power for about 16 hours a couple of years ago, and the backup worked the entire time and still had a good charge when it came back. Whew...

No, they have water powered ones -- they will work indefinitely, as long as you have water pressure. However they use roughly 2 gallons of water for every 1 gallon they remove. https://www.familyhandyman.com/basement/using-a-water-powered-backup-sump-pump/view-all/