Abstract: A leak detector apparatus and system for use with a plumbing fixture, appliance or other potential water leak source. The leak detector apparatus includes an electrically non-conducting mat that is shaped and dimensioned to rest on the floor. The mat comprises multiple layers of non-conducting closed cell foam and has a plurality of water collector cups formed therein. Spaced-apart sensor wires are provided and form a peripheral sensor that extends between the multiple layers of the mat body and the sensor wires generally extend through the water collector cups. The sensor wires are operative to sense the presence of water in the cups. An electronics module is provided and is associated with the sensor wires and electrically coupled to the sensor wires for triggering an alert in response to the presence of water in one or more of the cups.