Perhaps the most compact backyard water feature is a bubbling container. You can select nearly any size pot, slip in a pump and fountain and presto -- you've got the soothing sounds of bubbling water. Ideally, the decorative container you select will have a hole in the bottom, through which you can discreetly insert the pump's cord. If not, drill a hole yourself or leave the cord sticking out the back, then disguise it with greenery.
When choosing a spot for your container, it's best to set it in a nook or other area close to an outlet. If you don't do this, you'll need to use an extension cord, and extension cords can easily come unplugged. Plus, you'll have to hide more cord. If you're in a mosquito-prone area, you may wish to put two or three goldfish in the pot; they'll gobble up the larvae.
It's easy to let your imagination run wild when you're working with bubbling containers. Buy three pots of varying heights, for example, and set them in a decorative cluster. Or completely submerge your container(s) into the ground to make it appear as if water is bubbling up from an underground spring.