Method and device for detecting the flow of liquid, in particular water, in a consuming installation, comprising at least one opening/closing means (3) for supplying liquid, this installation being supplied via an inlet pipe (2) fitted with a solenoid valve (5), a pressure sensor (6) upstream of the solenoid valve and a pressure sensor (7) downstream of the solenoid valve. Management means (8) are able to effect the following operations: calculation of the difference (ΔP) between the value of the upstream pressure signal (Pam) and the value of the downstream pressure signal (Pav); comparison of this difference (ΔP) with at least one triggering threshold (SΔPo, SΔPf); when the pressure difference (ΔP) reaches or exceeds a triggering threshold (SΔPo), a command signal (Co) to open the solenoid valve (5) is generated; when the pressure difference (ΔP) reaches or falls below a triggering threshold (SΔPf), a command signal (Cf) to close the solenoid valve (5) is generated; and a flow signal (D) is generated as a function of said pressure difference (ΔP).