A sanitary hot water comprising a recirculating hot water (1) with: - an annular water duct (2), - a pump (3) connected to the ring line (2) at a point pumping (4) for circulating the water in the annular duct (2), - heating means (5) connected to the ring line (2) at a point heater (6) and configured to heat the water during the passage thereof through the heating stage (6), - one or more extraction lines (7) connected to the ring line (2) in the respective extraction points (8), - a supply conduit (9) connected to the duct ring (2) at a supply point (10)； wherein the domestic hot water system further comprises a disinfection system (11) having: - an electronic controller (12), - a generator of monochloramine (13) in signal connection with the control system (12) and connected to the ring line (2) in an insertion point of disinfectant (14), wherein the generator (13) is configured to synthesize monochloramine and adding the synthesized monochloramine to hot water, or is set directly synthesizing monochloramine in the hot water in the insertion point of disinfectant (14), - a reducing device ammonium ions (15) in signal connection with the control system (12) and connected to the annular conduit (2) at a point reduction (16), wherein the reduction device (15) is configured to add chlorine or hypochlorites water at point reduction (16), - detection means ammonium (17) in signal connection with the system control (12) and co nected with the annular conduit (2) at a detection point of ammonia (18), the detection means ammonium (17) configured to detect an amount representative of the concentration of ammonium ions in hot water at the point of ammonium detection (18), and to transmit a signal corresponding to the concentration control system (12) ammonium chloride； wherein the control system (12): - active generator monochloramine (13) and controls the synthesis and addition of monochloramine, and - enable reduction device ammonium (15) ions and control the addition of
