A field study has been carried out in the Picadilly Valley to check whether depletion of the sandstone aquifer is occurring in response to intensive pumping for vegetable irrigation. Groundwater samples have been taken from all domestic wells and some irrigation wells to check salinity and nitrate levels. Results show that there were no significant areas of depletion during March-April 1979, the time at which maximum groundwater usage was occurring. Nitrate levels were all below the W.H.O. maximum permissible level of 45 mg/1 with two exceptions, the maximum nitrate value recorded being 52 mg/1. No significant variations in salinity have been recorded in the area, and values are all below 500 mg/1 T.D.S. A network of 13 observation wells will be monitored by recording standing water levels plus nitrate and total dissolved solids values.