A sump pump alarm will alert you when your sump pit is about to overflow. Your sump pit will overflow because sooner or later, your sump pump will fail. It may fail when you expect it, such as when the power goes out in a storm. Or, it may fail quietly, unexpectedly, and you only discover it after your basement is flooded.
Your first line of defense is a high water alert system more commonly know as a sump pump alarm. The sump pump alarm will alert you when the water level reaches a certain level in your sump pit. This level that is preset by you. The alarm is electrically powered, and some alarms can be tied into your home security system.
A pump is triggered at a certain water level in the sump basin. The water level indicator for the sump pump alarm should be set at a water level higher that where the sump pump is triggered. If water reaches this level, it is an indication that there is a problem with your sump pump. When you hear this alarm, you need to react.
It also makes sense for your alarm have a battery backup. This way it will continue to work during a power failure. The alarm is most likely to sound during a power failure, especially if the failure is caused by a storm. It is raining after all. The rain ensures that there is a consistent supply of ground water for the pump to remove. But, since you have no power and your sump pump needs power to work, your pump will sit idle. The sump pit is most likely going to overflow. And just before it overflows, your battery backed sump pump alarm will sound alerting you to a potential flooded basement.
If your sump system fails due to a power outage, you have choices. You can rent or purchase a backup power generator. There are both gasoline and natural gas powered electrical generators available. You simply start the generator and plug your sump pump into it, and let it operate normally.
Another choice is to have a battery operated backup sump pump. You can either have this staged, ready to swap out with your electric sump pump when the power goes out, or you can have it installed "piggy-back", so that the battery operated sump pump works when the water level rises higher than what normally triggers your main sump.
If you have no power outage, hopefully the sump pump alarm will give you enough warning that you can either have your sump pump repaired, or time enough to buy and install a new replacement.