A safety device against leaks of liquid for a liquid-conducting household appliance or system, the device being designed for connection between a source of liquid and a liquid-conducting household appliance or system , the device comprising: - a first pipe for the liquid which comes from the source of liquid, - at least one hydraulic unit (11; 12), having a duct for the liquid, the at least one hydraulic unit being upstream of the first pipe or else downstream of the first pipe , - a flow sensor in the at least one hydraulic unit (11; 12), wherein the first pipe is connected in fluid communication with said duct and extends longitudinally at least in part within a second pipe that is impermeable to liquid, in such a way that defined between at least part of the first pipe and of the second pipe is a gap (G) having a proximal end and a distal end, wherein the at least one hydraulic unit (11; 12) has a respective hydraulic body (15; 16; 15 1 -15 2 ) that defines said duct , and wherein the device optionally comprises a valve arrangement (EV) that is electrically switchable between a closing position and an opening position, to prevent or enable, respectively, passage of liquid through the first pipe , characterized in that the flow sensor is a non-mechanical flow sensor that includes at least two first electrical detection elements (42; 42 1 , 42 2 , 42 3 ) within said duct , and in that the device further comprises an electrical and non-mechanical leak sensor in the at least one hydraulic unit (11; 12), the electrical and non-mechanical leak sensor comprising at least two electrodes prearranged for detecting possible leakage liquid having flown into the gap (G) and/or into a leakage detection chamber or volume . - a first pipe for the liquid which comes from the source of liquid, - at least one hydraulic unit (11; 12), having a duct for the liquid, the at least one hydraulic unit being upstream of the first pipe or else downstream of the first pipe , - a flow sensor in the at least one hydraulic unit (11; 12), wherein the first pipe is connected in fluid communication with said duct and extends longitudinally at least in part within a second pipe that is impermeable to liquid, in such a way that defined between at least part of the first pipe and of the second pipe is a gap (G) having a proximal end and a distal end, wherein the at least one hydraulic unit (11; 12) has a respective hydraulic body (15; 16; 15 1 -15 2 ) that defines said duct , and wherein the device optionally comprises a valve arrangement (EV) that is electrically switchable between a closing position and an opening position, to prevent or enable, respectively, passage of liquid through the first pipe , characterized in that the flow sensor is a non-mechanical flow sensor that includes at least two first electrical detection elements (42; 42 1 , 42 2 , 42 3 ) within said duct , and in that the device further comprises an electrical and non-mechanical leak sensor in the at least one hydraulic unit (11; 12), the electrical and non-mechanical leak sensor comprising at least two electrodes prearranged for detecting possible leakage liquid having flown into the gap (G) and/or into a leakage detection chamber or volume . <EOS>