Clean freshwater is essential for human life and health. But for the world’s poorest, it is often a scarce resource. This is due in large part to widespread destruction of wetlands and forests.

Wetlands, for example, act as giant sponges, absorbing rainfall and slowly releasing it over time. They are also highly efficient natural water treatment works, absorbing chemicals, filtering pollutants and sediments, breaking down suspended solids, and neutralising harmful bacteria. But since 1900, more than 50% of the world’s wetlands have disappeared - largely due to human activities.

Similarly, water from catchments with well-managed natural forests is almost always of higher quality, with less sediment and fewer pollutants, than water from those without. This is because natural forests minimize the risk of landslides, erosion, and sedimentation, and filter out pollutants such as pesticides. Some natural forests can even increase total water flow.

Around one-third of the world's largest cities – in developing and developed countries alike – rely on protected forests for some or all of their water supply requirements.

But in many cases, forest areas around big cities, including forest protected areas, are threatened by harmful activities, such as incompatible land use and logging.