The flowmeter of the present invention is primarily used in swimming pools and is configured to deactivate a swimming pool pump when the drain in the swimming pool is blocked or covered. Swimming pool drains are often blocked or covered by the body of a swimmer. When the drain is blocked or covered, the pump creates substantial suction force that entraps the body of a swimmer against the drain. By deactivating the pump when the drain is blocked or covered, the flowmeter of the present invention serves as a safety vacuum release system that prevents entrapment of a person by the drain of the swimming pool.