Unlined farm waste stores present a potential, but unquantified, risk to groundwater. Field studies of pore water retrieved from beneath active slurry stores indicate that there is a potential for pollutants to be transported down through the unsaturated zone of the aquifer. The highest risk to groundwater is where the water table is shallow, and/or where there is no protection offered to the aquifer by low-permeability soil or drift layers. A preliminary screening tool is presented, which highlights vulnerable areas of aquifer based on the protection offered by superficial layers. Two different approaches were applied, one utilizing soils data and the other making use of superficial geology data. Some of the differences between the approaches are considered, and their influence on the resulting risk assessment are discussed.