Abstract: The present apparatus is a novel locking apparatus and method for use with a shut-off valve. The housing of the locking apparatus is configured to receive at least a portion of the shut-off valve and secure it in a closed or off position. The housing of the locking device envelopes the shut-off valve and is secured in placed through the use of two screws. The screws have proprietary head shapes having a matching key. By using a housing which envelopes the shut-off valve and screws with proprietary head shapes, conventional methods to gain unauthorized access to the shut-off valve, such as lock picks, lock cutters, hammers, pry bars, and the like are ineffective.