The Gombe Sandstone is comparatively low permeability and the deeper Kerri-Kerri Formation remains poorly studied. The water table in the Sokoto Group varies widely between 20 and 100 meters deep, unconfined near the surface and confined in lower layers of the Gwandu Formation. Within the Sokoto Group, the Wurno Formation has moderate yields and limited recharge, while the Gundumi Formation conglomerates are good aquifers, with artesian conditions, bounded by deeper clay layers.