Laundry washing machine comprising an outer casing and, inside said outer casing, a washing tub, a rotatable drum housed in axially rotatable manner inside the washing tub and structured for housing the laundry to be washed, a detergent dispensing assembly which is structured for supplying detergent into the washing tub, a fresh-water supply circuit which is structured for selectively channeling a flow of fresh water from the water mains towards the detergent dispensing assembly and/or the washing tub, and a water softening device which is arranged/located along the fresh-water supply circuit and is structured for reducing the hardness degree of the fresh water channeled to the detergent dispensing assembly and/or to the washing tub; the water softening device in turn comprising: a water-softening agent container which is arranged/located along the fresh-water supply circuit and is filled with a water softening agent able to reduce the hardness degree of the fresh water flowing through the same water-softening agent container; a regeneration-agent reservoir which is fluidically connected to the water-softening agent container and comprises a manually-removable container which is structured to receive a consumable regeneration agent for performing a regeneration of the water softening function of the water softening agent stored into the water-softening agent container, and which is housed inside the casing in removable manner so as to be manually removed by the user at refilling of the regeneration agent; and a water supply circuit which is structured for channelling fresh water into the regeneration-agent reservoir so to at least partly dissolve the regeneration agents stored therein and form some brine; and an electrically-powered brine-circulating pump assembly or valve assembly which is interposed between the water-softening agent container and the regeneration-agent reservoir and is structured for regulating/controlling the outflow of the brine from the regeneration-agent reservoir to the water-softening agent container; wherein said manually removable container is a storage tank which is structured for being manually fillable with a given amount of said consumable regeneration agent; and wherein the water supply circuit and the brine-circulating pump assembly or valve assembly of the water softening device are both hydraulically connected to said storage tank in detachable manner, wherein the storage tank is structured so to be fitted/recessed in manually extractable manner into a corresponding tank seat realized on the casing, wherein the storage tank is provided with two hydraulic connectors (37, 38) which are structured to hydraulically connect in detachable manner the storage tank to, respectively, the water supply circuit of the water softening 20 device and to the brine-circulating pump assembly or valve assembly of the water softening device, wherein the two hydraulic connectors (37, 38) of the storage tank are structured so as to couple with corresponding complementary hydraulic connectors (39, 40) arranged/located on said tank seat, each respectively communicating with the water supply circuit of the water softening device and with the brine-circulating pump assembly or valve assembly of the water softening device, whereby the hydraulic connectors (37, 38) on the storage tank and the corresponding complementary hydraulic connectors (39, 40) on the tank seat are arranged so as to couple to one another during insertion of the storage tank into the tank seat.