Approximately a third of the world’s hundred largest cities rely on forest protected areas to supply a substantial amount of their drinking water. This book reports on the research that produced the statistics; demystifies the links between natural forests and water resources, including drinking water; looks at the environmental and social implications; and gives a number of detailed case studies from around the world. It is the first in what we plan to be a series of wider “arguments for protection” looking at wider benefits from protected areas.