Delivery device (1; 100) of a water jet, comprising a delivery head defining a delivery chamber, where said head comprises an inlet fitting suitable for connecting fluidically to a line for the supply of water into the delivery chamber, and a delivery plate wherein are obtained a plurality of water delivery nozzles present in the delivery chamber, wherein a safety valve is fixed to said delivery plate suitable for reducing the water pressure in the delivery chamber when the water pressure exceeds a preset pressure threshold, said safety valve comprising: - a hollow housing body which passes through and is integral with the delivery plate, wherein said hollow housing body is in fluidic communication with the delivery chamber through an inner body opening and is open to the exterior through an outer body opening facing in the direction of delivery of the water by the delivery nozzles; - a valve cartridge inserted tightly into the hollow housing body, the cartridge defining a valve seat for the passage of water from the inner body opening to the outer body opening and comprising an obturator movable between a closed position, wherein the obturator closes said valve seat, and an open position, wherein the obturator opens said valve seat when a pressure greater than the preset pressure threshold value acts on said obturator; - a support body connected in a removable way to the outer body opening of the hollow housing body, said support body having a bottom wall on which the valve cartridge rests and which is penetrated by through-openings for the evacuation to the outside of the water present in the hollow housing body, wherein the hollow housing body has an annular flat portion that extends radially from the outer side surface thereof and abuts against the inner side of the delivery plate when the support body is connected to the hollow housing body, characterized in that the support body comprises a threaded side wall suitable for screwing into the hollow housing body, and a base having a diameter larger than the outer diameter of the wall of the hollow housing body delimiting the outer body opening, so that when the support body is screwed into the hollow housing body, the annular flat portion is compressed against the inner side of the delivery plate. - a hollow housing body which passes through and is integral with the delivery plate, wherein said hollow housing body is in fluidic communication with the delivery chamber through an inner body opening and is open to the exterior through an outer body opening facing in the direction of delivery of the water by the delivery nozzles; - a valve cartridge inserted tightly into the hollow housing body, the cartridge defining a valve seat for the passage of water from the inner body opening to the outer body opening and comprising an obturator movable between a closed position, wherein the obturator closes said valve seat, and an open position, wherein the obturator opens said valve seat when a pressure greater than the preset pressure threshold value acts on said obturator; - a support body connected in a removable way to the outer body opening of the hollow housing body, said support body having a bottom wall on which the valve cartridge rests and which is penetrated by through-openings for the evacuation to the outside of the water present in the hollow housing body, wherein the hollow housing body has an annular flat portion that extends radially from the outer side surface thereof and abuts against the inner side of the delivery plate when the support body is connected to the hollow housing body,