During November and December 1977 a quantitative dye tracing programme was carried out on swallets draining into the Carboniferous Limestone above Burrington, on the northern flank of the Blackdown Pericline, Mendip. Results from the Rickford and Langford Resurgences, known to be the only outlets for the swallets, showed that most of the swallet water flowed to Rickford, suggesting a systematic division of swallet water underground. This has been used to propose a new model for the hydrology of the Burrington area, where swallets rapidly converge to a master conduit system, which then bifurcates, sending water to Rickford and Langford. The larger discharge at Rickford Resurgence is due to the eastward extension to Lamb Leer Cavern, taking in a large area of the limestone plateau, providing a source area for percolation water which makes up some 95% of Rickford’s discharge.