Abstract: The safety device makes it possible to cut the water supply off quickly when there is a very low flow of water such as occurs when there is a leak, to cut off the water supply after predetermined time with normal water consumption, and to cut the water supply off very quickly when a certain predetermined maximum flow is exceeded as would occur with a fractured pipe. The safety device is automatically returned to its initial position when the water consumption is stopped and the shut off is first indicated by a significant reduction in flow. The device can also be manually returned to its initial position after a shut-off.