Battery–powered sump pumps are the most popular backup sump pump. They are powered by a deep cycle marine battery that maintains a charge through a trickle charger. This type of pump is frequently available in an assembly that includes the primary pump and are connected to the same drain line. Installation is easy and can be done by most homeowners. Battery backups can operate continuously for 4 to 5 hours or intermittently for as long as a day.
Water-powered backup sump pumps are an alternative to battery-powered pumps. As opposed to 120 V or battery backup pumps, water-powered pumps do not require an external electric power source. Instead, they are powered by the municipal water supply. Since the water is constantly flowing, the pump will continue to operate even during extended power outages.
As with battery-powered backup pumps, the water-powered pump is mounted above the float for the main pump and contains its own float.
Water-powered backup pumps operate on the principle of the Venturi effect. When the float for the backup pump is activated, it opens a valve connected to the municipal water supply. The municipal water flows through a constricted area in the pump ejector that increases the water velocity and reduces the pressure. This results in a suction that draws the water from the sump through a drain line and discharges it outside the house. Two gallons of water can be pumped for every gallon of municipal water. They are more expensive and complicated to install than battery-powered pumps, but they can be worth the effort and money in areas prone to flooding or power outages.
