Abstract: A modular system for holding water cooler bottles on their sides so as to be easily stored and readily accessible for removal and placement in a water cooler. The present invention is an integrally formed molded plastic bottle holder unit which is vertically stackably interconnectable and horizontally interconnectable to form a bottle holder system. Each unit has four vertical supports. Two parallel horizontal supports are provided, each integrally formed with and connecting a pair of vertical supports. These pairs of connected vertical supports are connected by two horizontal supports each shaped and arcuately contoured to support the curved side of a water bottle. An integrally formed horizontal support member extends between the two contoured horizontal support members substantially parallel to the bottle longitudinal axis.