Provided is a backup water-source filtration system, comprising a filtration apparatus, a water pump, a soft-water device, and a reverse osmosis (RO) apparatus; the filtration apparatus, soft-water device, and RO apparatus are connected in series; the inlet of the filtration apparatus is connected to a backup water source, and the outlet of the RO apparatus is connected to a downstream water-production device. By means of filtering, softening, and RO, the backup water-source filtration system removes impurities, bacteria, and salt from the water, satisfying the conditions of starting water for a downstream water-production device and increasing the service life of a downstream water-production device.
