The smallest fountains are designed for tabletops. These units may be no larger than the basin of a bathroom sink. They're typically self-contained. Tabletop fountains are great options for offices, studio apartments and other relatively small spaces (and you'll be amazed at how much more space you seem to have when the air is full of the sound of flowing water). You should, of course, make sure there's some sort of protection for the table surface -- a fountain can cause both water damage and nicks and scrapes. It's also a good idea to check the stability and placement of the table itself -- you don't want to put a bowl full of water on the wobbly end table everyone always bumps into on their way into the TV room.
Floor fountains are often freestanding. These models are often "statement" pieces designed for indoor or outdoor use. They're bigger and heavier than tabletop fountains, so you should make sure the floor is sturdy enough to support such a weight. (Remember to think about the fountain's weight when full, not just its weight in the package. Water is heavy.)
Wall fountains, as the name implies, are wall-mounted. That involves a whole other set of installation questions: What are your walls made of? Are they strong enough to hold up a fountain? Drywall and sheetrock can't support heavy fountains, so don't even try. Are you inviting water damage? If you can resolve these issues satisfactorily, a wall fountain can add a dramatic cascade of water to your home or garden.
Garden fountains can range from traditional classical styles -- the sort that wouldn't be out of place among the sculpted topiary of 18th-century gardens -- to modern series of bowls nestled into the ground. They may involve statues or other decoration. To install a garden fountain, you may want to do a little excavation. You can go with a ready-made variety, or -- for a bit more effort and not much expense -- use the garden's natural topography to create a connected series of pools.
With garden fountains, think about the landscaping. Consider any overhanging trees or shrubs. If they shed leaves, you'll need to clean leaves from the fountain periodically to keep them from clogging the pump or decomposing into unsightly muck -- even if there aren't any plants in the direct vicinity, you'll still need to clean out the pump every so often. Make sure you're up to the maintenance demands of an outdoor fountain.
Now that you've chosen a fountain, what goes into its installation? Read on.