Water is the stuff of life. From a biological point of view, every living being needs it to survive. From the artistic point of view, water adds a special extra ingredient that can be the making of a garden. A great many designers refuse to contemplate a garden plan without water and frequently it plays a central role in their landscapes. But, like all hard landscape features, water can be overdone and an insensitive or self-indulgent designer may ruin a good thing by having too many water courses, fountains and pools.
Yet a garden with water is almost always more interesting than one without. Water features provide another key to an established feel. Although sometimes costly, they are quick and easy to install, and can be designed to suite every imaginable style of garden from a natural wildlife pool to a Persian-style rill that might grace a harem.
Nigel Colburn, 'Shortcuts To Great Gardens'