Akin to both waterfalls and birdbaths, water basins are decorative bowls that catch water dripping or pouring from a nearby spout. When the basin fills, it overflows, generally onto decorative rocks that hide a reservoir buried under the ground. The water is then recirculated from the reservoir back into the spout. Basins can be made from a variety of materials, including hand-hammered copper, aluminum, stone or wood. Similarly, the spouts can be crafted from materials like bamboo, if you're going for an Asian look, or any of a variety of metals.
Water basins have their roots in Japanese garden design. Chozubachi basins, for example, are set near the garden gate with a ladle so guests can have a drink or splash some cool water on their brow in a ritual suggesting forgiveness. Tsukubai basins have no ladles and are set low so visitors have to bend to reach the water in an act of reverence, indicating you're entering a sacred portion of the garden.