Devices, systems, and methods for coupling tubing to a fluid reservoir to provide liquid to an endoscope system. A manifold for coupling to a fluid reservoir and a tubing assembly may include first portion interfacing with an interior of the fluid reservoir and a second portion configured to interface with tubing to be fluidly coupled to the interior of the reservoir. The first portion may include one or more openings to allow gas to pass into the fluid reservoir and liquid to pass out of the fluid reservoir. The second portion may include one or more ports for connecting to tubing that brings gas to the fluid reservoir and receives liquid from the fluid reservoir. The manifold may include a valve that selectively allows gas to pass into the fluid reservoir.