Radiocarbon (14C) conclusively demonstrates that the very important Yarkon-Tanininm aquifer, named after the two springs where the drainage presumably occurs, is in actuality two distinct aquifers—Upper and Lower. The springs have higher 14C activities than the exploitation wells that surround them (all drilled into the Upper aquifer). The springs are situated at faults that allow the Lower aquifer water to rise due to its higher pieziometric head and drain along with the Upper aquifer. The Lower aquifer water flows rapidly along a path that includes a karstic system. The Upper aquifer flows more slowly, primarily through a system of cracks in the carbonate aquifer. The Upper aquifer groundwater in the Beer-Sheba extension flows northwards at approximately ~4–7 m/yr.