Open water (blue): rivers and streams (500 hectares); standing water (1,500 hectares). Marshy land and reed-beds (green).

The main areas of open water are the gravel pits along the main rivers, the Kennett, Loddon and Thames, together with Queen Mother Reservoir, the largest open water in Berkshire.  Most of the wet grassland in the river valleys has been drained though transient areas of open water collect on the floodplains in most winters.