Leon A. Hausman's rules for creating a birdbath include: 1. Place the birdbath near trees and shrubs but not beneath them. A shaded birdbath does not offer enough sunlight and air to dry a bird's feathers; 2. The depth of water in the birdbath should not exceed 2 inches. In fact, two inches of water is too much. If you insist on two inches of water, flat pebbles should be placed in the bottom of the bath so the water level is below the height of a bird's legs; 3. Birds like dripping or running water.
In A Beginner's Guide to Attracting Birds, Hausman (1951) categorizes birdbaths and drinking into two types: the ground bath and the elevated bath. An elevated bath can be constructed by placing a shallow dish, pan, or piece of pottery on a stump or upturned log, or a manufactured bath can be used.
A shallow dish placed on the ground can serve as a ground bath. Another way to make a ground bath is to create a hollow in the soil and line it with cement or concrete, or metal (not shiny or slippery), or glazed pottery. Ground baths can also be made from wood. To create a dripping effect, a slightly tipped pail, with water, can be hung over a shallow basin. You could also alter a standard yard water fountain into a bird fountain (Lowe's has a DIY water fountain kit).
Humans also use drinking fountains, though not as baths.
Municipal waterfront park, Charleston, SC