Figure 9.25
The potentiometric surface. (A) The potentiometric surface can be visualized as a dome with a surface that drops in all directions with distance away from the water supply. The house farthest from this water tower will have poor water pressure because it is at the level of the potentiometric surface. (B) Water tanks in New York City provide water pressure for the buildings on which they sit. Modern skyscrapers use mechanical pumps, rather than water tanks, to provide water pressure to the building.(B. © John Cairns/Alamy)