The WellMaster database holds hydrogeological information on water wells for wells and boreholes identified within the Single Onshore Borehole Index (SOBI) within England Wales and Scotland. The database contains index details supplementary to SOBI, including information on the availability of more detailed hydrogeological information. Four main categories of data are held within the database; lithostratigraphic details, well/borehole construction including casing and screens, water information including depths and pumping rates and water quality information.