Building water safety system, comprising - a shut-off valve with an inlet opening and an outlet opening, a valve passage which connects the inlet opening to the outlet opening and a shut-off member which opens the valve passage for the medium to flow from the inlet opening to the outlet opening when in an open position and closes it when in a closed position, - an actuator, in particular an electro-mechanically operated actuator, which is mechanically coupled with the shut-off member and which is configured to move the shut-off member out of the open position into the closed position and vice versa, - a sensor device for detecting the presence of a person in the area of a water drawing point, - a control system coupled by signal communication with the sensor device and the actuator, which is configured to o activate the actuator in order to move the shut-off member into the open position on receiving a sensor signal from the sensor device signalling the presence of a person in the area of the water drawing point and/or o activate the actuator in order to move the shut-off member into the closed position on receiving a sensor signal from the sensor device signalling the absence of a person in the area of the water drawing point, - a switch device (72, 73) which is coupled with the control system by signal communication and which is configured to detect a switch-on operation of a water-consuming device and send a signal to the control system in order to open the shut-off valve, characterised in that the switch device comprises a sensor which is configured to detect the switching status or a switching operation of an electromagnetic peripheral shut-off valve to which the water-consuming device is connected, and the switch-on operation is detected on the basis of an opening operation of the peripheral shut-off valve. - a shut-off valve with an inlet opening and an outlet opening, a valve passage which connects the inlet opening to the outlet opening and a shut-off member which opens the valve passage for the medium to flow from the inlet opening to the outlet opening when in an open position and closes it when in a closed position, - an actuator, in particular an electro-mechanically operated actuator, which is mechanically coupled with the shut-off member and which is configured to move the shut-off member out of the open position into the closed position and vice versa, - a sensor device for detecting the presence of a person in the area of a water drawing point, - a control system coupled by signal communication with the sensor device and the actuator, which is configured to o activate the actuator in order to move the shut-off member into the open position on receiving a sensor signal from the sensor device signalling the presence of a person in the area of the water drawing point and/or o activate the actuator in order to move the shut-off member into the closed position on receiving a sensor signal from the sensor device signalling the absence of a person in the area of the water drawing point, o activate the actuator in order to move the shut-off member into the open position on receiving a sensor signal from the sensor device signalling the presence of a person in the area of the water drawing point and/or o activate the actuator in order to move the shut-off member into the closed position on receiving a sensor signal from the sensor device signalling the absence of a person in the area of the water drawing point, - a switch device (72, 73) which is coupled with the control system by signal communication and which is configured to detect a switch-on operation of a water-consuming device and send a signal to the control system in order to open the shut-off valve, and the switch-on operation is detected on the basis of an opening operation of the peripheral shut-off valve.