Cut the caramel into large pieces. Combine caramel and water in a heavy-bottomed pot. Heat over medium-low heat until the caramel melts. Stir constantly to prevent burning. 

Once all the caramels have melted and the mixture is smooth, add the half and half. The sauce will bubble up and then settle down. Stir to combine.

Remove the pan from the heat and pour sauce into two heatproof jars. 

Store caramel sauce in the refrigerator for up to four weeks.