A water heater can include a housing and a heating system disposed within the housing, where the heating system is configured to heat a fluid. The water heater can also include a switch coupled to the heating system, where the switch operates between a first position during normal operations and a second position during an outage. The water heater can further include a primary power source coupled to the switch, where the primary power source is configured to provide primary power to the heating system through the switch during the normal operations. The water heater can also include an uninterruptible power supply (UPS) coupled to the switch, where the UPS is configured to provide reserve power to the heating system through the switch during the outage, and where the UPS is integrated with the housing.