A thermal dispersion flow meter with chronometric monitor for fluid leak detection includes an ambient temperature RTD sensor and a flow rate RTD sensor which are configured to sense the temperature of a fluid in a conduit, and then monitor the flow of that fluid through the conduit. The fluid flow RTD sensor is incorporated into a Wheatstone bridge circuit which is used to provide increased sensitivity to the outputs of the RTD sensors. Based upon the ambient temperature sensor readings, the flow rate RTD sensor may be adjusted to optimize the operation of the system to detect leaks, and on certain conditions, a controller may close a supply line valve to avoid flooding of a structure.