The assemblies of the invention are suitable for mounting to or being an Integral part of, an animal enclosure such that the height of a valve-controlled liquid outlet may be adjusted according to the changing needs of growing animals The adjustable liquid delivery assemblies comprise an elongated rail, a liquid delivery unit having at least one liquid delivery head slideably engaged with the elongated rail, a flexible liquid delivery tube for connecting a liquid delivery head to a liquid source, and a means for securing the liquid delivery unit at a selected position on the elongated rail The liquid delivery system may further comprise a retaining rail A means for securing the liquid delivery unit at a selected position on the elongated rail may comprise a linear series of holes disposed along the length of the rail.
