An electromagnetic induction continuous-flow water heater (2, 102, 302, 403, 502, 602, 702, 802, 902, 1002, 1102, 1202, 1302, 1402, 1502, 1602, 1702, 1802, 1902, 2002, 2102, 2202), in particular for an automatic beverage vending machine; the heater comprises: - a tubular body (8, 108, 208) having a longitudinal axis and including at least one inlet, configured to receive water to be heated and to feed it, in use, into the tubular body (8, 108, 208), and an outlet, through which the heated water flows out of the tubular body (8, 108, 208); and - an electrical winding wound around the tubular body (8, 108, 208) and electrically powerable to generate an electromagnetic induction field; the tubular body (8, 108, 208) is made of an electrically conductive material so that it is heated by electromagnetic induction due to the effect of said electromagnetic induction field; the heater further comprises an insert (18, 118, 718, 1118, 1218, 1318, 1418, 1518, 1618, 1718, 1818, 1918, 2018, 2118, 2218) housed inside the tubular body (8, 108, 208) and extending along the longitudinal axis; characterized in that the heater further comprises a helical flow channel (23, 123, 223, 323, 423, 523, 623, 723, 823, 923, 1023, 1123, 1223, 1323, 1423, 1523, 1623, 1723, 1823, 1923, 2023, 2123, 2223) for the water, which extends helically around the longitudinal axis and is delimited by the internal surface (22, 122, 222) of the tubular body (8, 108, 208) and the external surface (21, 121, 721, 1121, 1221, 1321, 1421, 1521, 1621, 1721, 1821, 1921, 2021, 2121, 2221) of the insert. the heater comprises: - a tubular body (8, 108, 208) having a longitudinal axis and including at least one inlet, configured to receive water to be heated and to feed it, in use, into the tubular body (8, 108, 208), and an outlet, through which the heated water flows out of the tubular body (8, 108, 208); and - an electrical winding wound around the tubular body (8, 108, 208) and electrically powerable to generate an electromagnetic induction field; - a tubular body (8, 108, 208) having a longitudinal axis and including at least one inlet, configured to receive water to be heated and to feed it, in use, into the tubular body (8, 108, 208), and an outlet, through which the heated water flows out of the tubular body (8, 108, 208); and - an electrical winding wound around the tubular body (8, 108, 208) and electrically powerable to generate an electromagnetic induction field; the tubular body (8, 108, 208) is made of an electrically conductive material so that it is heated by electromagnetic induction due to the effect of said electromagnetic induction field; the heater further comprises an insert (18, 118, 718, 1118, 1218, 1318, 1418, 1518, 1618, 1718, 1818, 1918, 2018, 2118, 2218) housed inside the tubular body (8, 108, 208) and extending along the longitudinal axis; characterized in that the heater further comprises a helical flow channel (23, 123, 223, 323, 423, 523, 623, 723, 823, 923, 1023, 1123, 1223, 1323, 1423, 1523, 1623, 1723, 1823, 1923, 2023, 2123, 2223) for the water, which extends helically around the longitudinal axis and is delimited by the internal surface (22, 122, 222) of the tubular body (8, 108, 208) and the external surface (21, 121, 721, 1121, 1221, 1321, 1421, 1521, 1621, 1721, 1821, 1921, 2021, 2121, 2221) of the insert.