The present invention discloses an easy-to-use, installation-free water leak warning device having a sturdy hollow body enclosing essential functioning elements including a power source, an amplifier, a speaker, and portions of two electrodes. The water leak warning device is preferably small in size and may be placed at potential water leak or flooding spots. The essential functioning elements are operatively connected with conductive material so that when leaked water flows to where the device is located, an audible signal can be emitted to remind the user of the device to prevent further leakage and mitigate any damage.