Water features add tremendous value to a garden. They engage all the senses. In an urban environment, the sound of water becomes an important feature to cover the noise of the city and immediately transport the visitor. Standing water can provide a home for mosquitoes and other pest insects, so moving water is preferred. Waterfalls are an effective way to maximize the impact of water in an urban environment. With a recirculating water, you get motion and sound without standing water.
For cooling purposes, misting systems are highly effective. In the humidity of New York summer, the mist appears cloud-like and provides a mysterious effect. In the courtyard a misting system can be incorporated into the face of the building and provide relief for the few unshaded areas during the hottest summer days.
Water features require a recirculating pump, preferably with a u.v. filter to discourage the formation of bacteria if it is accessible for people to touch. This can be connected to the water line and an electrical source.